diff --git a/db/builder_db.ml b/db/builder_db.ml
index c8c68a5..fcc1aa2 100644
--- a/db/builder_db.ml
+++ b/db/builder_db.ml
@@ -242,6 +242,7 @@ module Build = struct
     console : (int * string) list;
     script : string;
     main_binary : [`build_artifact] id option;
+    input_id : Cstruct.t option;
     user_id : [`user] id;
     job_id : [`job] id;
   }
@@ -257,17 +258,18 @@ module Build = struct
                        (tup2
                           execution_result
                           console)
-                       (tup2
+                       (tup3
                           string
-                          (option (Rep.id `build_artifact))))
+                          (option (Rep.id `build_artifact))
+                          (option Rep.cstruct)))
                     (id `user)
                     (id `job))
     in
-    let encode { uuid; start; finish; result; console; script; main_binary; user_id; job_id } =
-      Ok ((uuid, (start, finish), (result, console), (script, main_binary)), user_id, job_id)
+    let encode { uuid; start; finish; result; console; script; main_binary; input_id; user_id; job_id } =
+      Ok ((uuid, (start, finish), (result, console), (script, main_binary, input_id)), user_id, job_id)
     in
-    let decode ((uuid, (start, finish), (result, console), (script, main_binary)), user_id, job_id) =
-      Ok { uuid; start; finish; result; console; script; main_binary; user_id; job_id }
+    let decode ((uuid, (start, finish), (result, console), (script, main_binary, input_id)), user_id, job_id) =
+      Ok { uuid; start; finish; result; console; script; main_binary; input_id; user_id; job_id }
     in
     Caqti_type.custom ~encode ~decode rep
 
@@ -278,6 +280,7 @@ module Build = struct
       finish : Ptime.t;
       result : Builder.execution_result;
       main_binary : [`build_artifact] id option;
+      input_id : Cstruct.t option;
       user_id : [`user] id;
       job_id : [`job] id;
     }
@@ -291,15 +294,17 @@ module Build = struct
                           Rep.ptime
                           Rep.ptime)
                        execution_result
-                       (option (Rep.id `build_artifact)))
+                       (tup2
+                          (option (Rep.id `build_artifact))
+                          (option Rep.cstruct)))
                      (id `user)
                      (id `job))
       in
-      let encode { uuid; start; finish; result; main_binary; user_id; job_id } =
-        Ok ((uuid, (start, finish), result, main_binary), user_id, job_id)
+      let encode { uuid; start; finish; result; main_binary; input_id; user_id; job_id } =
+        Ok ((uuid, (start, finish), result, (main_binary, input_id)), user_id, job_id)
       in
-      let decode ((uuid, (start, finish), result, main_binary), user_id, job_id) =
-        Ok { uuid; start; finish; result; main_binary; user_id; job_id }
+      let decode ((uuid, (start, finish), result, (main_binary, input_id)), user_id, job_id) =
+        Ok { uuid; start; finish; result; main_binary; input_id; user_id; job_id }
       in
       Caqti_type.custom ~encode ~decode rep
   end
@@ -341,7 +346,7 @@ module Build = struct
       t
       {| SELECT uuid, start_d, start_ps, finish_d, finish_ps,
                 result_kind, result_code, result_msg,
-                console, script, main_binary, user, job
+                console, script, main_binary, input_id, user, job
            FROM build
            WHERE id = ?
         |}
@@ -352,7 +357,7 @@ module Build = struct
       (Caqti_type.tup2 (id `build) t)
       {| SELECT id, uuid, start_d, start_ps, finish_d, finish_ps,
                   result_kind, result_code, result_msg,
-                  console, script, main_binary, user, job
+                  console, script, main_binary, input_id, user, job
            FROM build
            WHERE uuid = ?
         |}
@@ -363,7 +368,7 @@ module Build = struct
       (Caqti_type.tup2 (id `build) t)
       {| SELECT id, uuid, start_d, start_ps, finish_d, finish_ps,
                   result_kind, result_code, result_msg, console,
-                  script, main_binary, user, job
+                  script, main_binary, input_id, user, job
            FROM build
            WHERE job = ?
            ORDER BY start_d DESC, start_ps DESC
@@ -377,15 +382,38 @@ module Build = struct
       {| SELECT build.id, build.uuid,
                 build.start_d, build.start_ps, build.finish_d, build.finish_ps,
                 build.result_kind, build.result_code, build.result_msg,
-                build.main_binary, build.user, build.job,
+                build.main_binary, build.input_id, build.user, build.job,
                 build_artifact.filepath, build_artifact.localpath, build_artifact.sha256, build_artifact.size
            FROM build, job
            LEFT JOIN build_artifact ON
              build.main_binary = build_artifact.id
            WHERE job.id = ? AND build.job = job.id
-           ORDER BY start_d DESC, start_ps DESC
+           ORDER BY build.start_d DESC, build.start_ps DESC
         |}
 
+  let get_all_artifact_sha =
+    Caqti_request.collect
+      (id `job)
+      Rep.cstruct
+      {| SELECT DISTINCT a.sha256
+         FROM build_artifact a, build b
+         WHERE b.job = ? AND b.main_binary = a.id
+         ORDER BY b.start_d DESC, b.start_ps DESC
+      |}
+
+  let get_latest_failed =
+    Caqti_request.find_opt
+      (id `job)
+      Meta.t
+      {| SELECT uuid, start_d, start_ps, finish_d, finish_ps,
+                result_kind, result_code, result_msg,
+                main_binary, input_id, user, job
+         FROM build
+         WHERE job = ? AND result_kind <> 0 OR result_code <> 0
+         ORDER BY start_d DESC, start_ps DESC
+         LIMIT 1
+      |}
+
   let get_latest =
     Caqti_request.find_opt
       (id `job)
@@ -396,13 +424,13 @@ module Build = struct
       {| SELECT b.id,
            b.uuid, b.start_d, b.start_ps, b.finish_d, b.finish_ps,
            b.result_kind, b.result_code, b.result_msg,
-           b.main_binary, b.user, b.job,
+           b.main_binary, b.input_id, b.user, b.job,
            a.filepath, a.localpath, a.sha256, a.size
          FROM build b
          LEFT JOIN build_artifact a ON
            b.main_binary = a.id
          WHERE b.job = ?
-         ORDER BY start_d DESC, start_ps DESC
+         ORDER BY b.start_d DESC, b.start_ps DESC
          LIMIT 1
       |}
 
@@ -413,7 +441,7 @@ module Build = struct
       {| SELECT b.id, b.uuid
          FROM build b
          WHERE b.job = ?
-         ORDER BY start_d DESC, start_ps DESC
+         ORDER BY b.start_d DESC, b.start_ps DESC
          LIMIT 1
       |}
 
@@ -424,7 +452,7 @@ module Build = struct
       {| SELECT b.uuid
          FROM build b
          WHERE b.job = ? AND b.result_kind = 0 AND b.result_code = 0
-         ORDER BY start_d DESC, start_ps DESC
+         ORDER BY b.start_d DESC, b.start_ps DESC
          LIMIT 1
       |}
 
@@ -435,7 +463,7 @@ module Build = struct
       {| SELECT b.id,
            b.uuid, b.start_d, b.start_ps, b.finish_d, b.finish_ps,
            b.result_kind, b.result_code, b.result_msg,
-           b.main_binary, b.user, b.job
+           b.main_binary, b.input_id, b.user, b.job
          FROM build b, build b0
          WHERE b0.id = ? AND b0.job = b.job AND
            b.result_kind = 0 AND b.result_code = 0 AND
@@ -444,28 +472,93 @@ module Build = struct
          LIMIT 1
       |}
 
-  let get_other_builds_with_same_output =
+  let get_same_input_same_output_builds =
     Caqti_request.collect
       (id `build)
       Meta.t
       {| SELECT b.uuid, b.start_d, b.start_ps, b.finish_d, b.finish_ps,
            b.result_kind, b.result_code, b.result_msg,
-           b.main_binary, b.user, b.job
+           b.main_binary, b.input_id, b.user, b.job
          FROM build b0, build_artifact a0, build b, build_artifact a
-         WHERE b0.id = ? AND a0.id = b0.main_binary AND a0.sha256 = a.sha256 AND b.main_binary = a.id AND b.id <> b0.id
+         WHERE b0.id = ? AND a0.id = b0.main_binary AND a0.sha256 = a.sha256
+           AND b.main_binary = a.id AND b.id <> b0.id AND b0.input_id = b.input_id
          ORDER BY b.start_d DESC, b.start_ps DESC
       |}
 
+  let get_same_input_different_output_hashes =
+    Caqti_request.collect
+      (id `build)
+      Rep.cstruct
+      {| SELECT DISTINCT a.sha256
+         FROM build b0, build_artifact a0, build b, build_artifact a
+         WHERE b0.id = ? AND a0.id = b0.main_binary AND a0.sha256 <> a.sha256
+           AND b.main_binary = a.id AND b.id <> b0.id AND b0.input_id = b.input_id
+         ORDER BY b.start_d DESC, b.start_ps DESC
+      |}
+
+  let get_different_input_same_output_input_ids =
+    Caqti_request.collect
+      (id `build)
+      Rep.cstruct
+      {| SELECT DISTINCT b.input_id
+         FROM build b0, build_artifact a0, build b, build_artifact a
+         WHERE b0.id = ? AND a0.id = b0.main_binary AND a0.sha256 = a.sha256
+           AND b.main_binary = a.id AND b0.input_id <> b.input_id
+      |}
+
+  let get_one_by_input_id =
+    Caqti_request.find
+      Rep.cstruct
+      Meta.t
+      {| SELECT uuid, start_d, start_ps, finish_d, finish_ps,
+          result_kind, result_code, result_msg,
+          main_binary, input_id, user, job
+         FROM build
+         WHERE input_id = ?
+         ORDER BY start_d DESC, start_ps DESC
+         LIMIT 1
+      |}
+
   let add =
     Caqti_request.exec
-      (Caqti_type.tup2 t (Caqti_type.option cstruct))
+      t
       {| INSERT INTO build
            (uuid, start_d, start_ps, finish_d, finish_ps,
-           result_kind, result_code, result_msg, console, script, main_binary, user, job, input_id)
+           result_kind, result_code, result_msg, console, script, main_binary, input_id, user, job)
            VALUES
            (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
         |}
 
+  let get_meta_by_hash =
+    Caqti_request.find
+      Rep.cstruct
+      Meta.t
+      {| SELECT
+           b.uuid, b.start_d, b.start_ps, b.finish_d, b.finish_ps,
+           b.result_kind, b.result_code, b.result_msg,
+           b.main_binary, b.input_id, b.user, b.job
+         FROM build_artifact a
+         INNER JOIN build b ON b.id = a.build
+         WHERE a.sha256 = ?
+         ORDER BY b.start_d DESC, b.start_ps DESC
+         LIMIT 1
+      |}
+
+  let get_meta_and_artifact_by_hash =
+    Caqti_request.find
+      Rep.cstruct
+      (Caqti_type.tup2 Meta.t file_opt)
+      {| SELECT b.uuid, b.start_d, b.start_ps, b.finish_d, b.finish_ps,
+                b.result_kind, b.result_code, b.result_msg,
+                b.main_binary, b.input_id, b.user, b.job,
+                a.filepath, a.localpath, a.sha256, a.size
+           FROM build_artifact a
+           INNER JOIN build b ON b.id = a.build
+           WHERE a.sha256 = ?
+           ORDER BY b.start_d DESC, b.start_ps DESC
+           LIMIT 1
+        |}
+
   let get_by_hash =
     Caqti_request.find_opt
       Rep.cstruct
@@ -475,7 +568,7 @@ module Build = struct
       {| SELECT job.name,
            b.uuid, b.start_d, b.start_ps, b.finish_d, b.finish_ps,
            b.result_kind, b.result_code, b.result_msg,
-           b.console, b.script, b.main_binary, b.user, b.job
+           b.console, b.script, b.main_binary, b.input_id, b.user, b.job
          FROM build_artifact a
          INNER JOIN build b ON b.id = a.build
          INNER JOIN job ON job.id = b.job
diff --git a/db/builder_db.mli b/db/builder_db.mli
index 00fffd3..0a87040 100644
--- a/db/builder_db.mli
+++ b/db/builder_db.mli
@@ -127,6 +127,7 @@ sig
     console : (int * string) list;
     script : string;
     main_binary : [`build_artifact] id option;
+    input_id : Cstruct.t option;
     user_id : [`user] id;
     job_id : [`job] id;
   }
@@ -138,6 +139,7 @@ sig
       finish : Ptime.t;
       result : Builder.execution_result;
       main_binary : [`build_artifact] id option;
+      input_id : Cstruct.t option;
       user_id : [`user] id;
       job_id : [`job] id;
     }
@@ -157,9 +159,13 @@ sig
     ([`job] id, [`build] id * t, [ `Many | `One | `Zero ]) Caqti_request.t
   val get_all_meta :
     ([`job] id, [`build] id * Meta.t * file option, [ `Many | `One | `Zero ]) Caqti_request.t
+  val get_all_artifact_sha :
+    ([`job] id, Cstruct.t, [ `Many | `One | `Zero ]) Caqti_request.t
   val get_latest :
     ([`job] id, [`build] id * Meta.t * file option, [< `Many | `One | `Zero > `One `Zero ])
       Caqti_request.t
+  val get_latest_failed :
+    ([`job] id, Meta.t, [< `Many | `One | `Zero > `One `Zero ]) Caqti_request.t
   val get_latest_uuid :
     ([`job] id, [`build] id * Uuidm.t, [< `Many | `One | `Zero > `One `Zero ])
       Caqti_request.t
@@ -169,9 +175,19 @@ sig
   val get_previous_successful :
     ([`build] id, [`build] id * Meta.t, [< `Many | `One | `Zero > `One `Zero ])
       Caqti_request.t
-  val get_other_builds_with_same_output :
+  val get_same_input_same_output_builds :
     ([`build] id, Meta.t, [ `Many | `One | `Zero ]) Caqti_request.t
-  val add : (t * Cstruct.t option, unit, [< `Many | `One | `Zero > `Zero ]) Caqti_request.t
+  val get_same_input_different_output_hashes :
+    ([`build] id, Cstruct.t, [ `Many | `One | `Zero ]) Caqti_request.t
+  val get_different_input_same_output_input_ids :
+    ([`build] id, Cstruct.t, [ `Many | `One | `Zero ]) Caqti_request.t
+  val get_one_by_input_id :
+    (Cstruct.t, Meta.t, [< `Many | `One | `Zero > `One ]) Caqti_request.t
+  val add : (t, unit, [< `Many | `One | `Zero > `Zero ]) Caqti_request.t
+  val get_meta_by_hash :
+    (Cstruct.t, Meta.t, [< `Many | `One | `Zero > `One]) Caqti_request.t
+  val get_meta_and_artifact_by_hash :
+    (Cstruct.t, Meta.t * file option, [< `Many | `One | `Zero > `One]) Caqti_request.t
   val get_by_hash :
     (Cstruct.t, string * t, [< `Many | `One | `Zero > `One `Zero]) Caqti_request.t
   val set_main_binary : ([`build] id * [`build_artifact] id, unit, [< `Many | `One | `Zero > `Zero ]) Caqti_request.t
diff --git a/lib/builder_web.ml b/lib/builder_web.ml
index 6df7f41..d468ef9 100644
--- a/lib/builder_web.ml
+++ b/lib/builder_web.ml
@@ -137,14 +137,15 @@ let add_routes datadir =
     (Dream.sql req (Model.readme job_name) >>= fun readme ->
      Dream.sql req (Model.build uuid) >>= fun (build_id, build) ->
      Dream.sql req (Model.build_artifacts build_id) >>= fun artifacts ->
-     Dream.sql req (Model.builds_with_same_main_binary build_id) >>= fun other_builds ->
-     Dream.sql req (Model.latest_successful_build_uuid build.job_id) >>= fun latest_uuid ->
-     Dream.sql req (Model.previous_successful_build build_id) >|= fun previous_build ->
-         (readme, build, artifacts, other_builds, latest_uuid, previous_build))
+     Dream.sql req (Model.builds_with_same_input_and_same_main_binary build_id) >>= fun same_input_same_output ->
+     Dream.sql req (Model.builds_with_different_input_and_same_main_binary build_id) >>= fun different_input_same_output ->
+     Dream.sql req (Model.builds_with_same_input_and_different_main_binary build_id) >>= fun same_input_different_output ->
+     Dream.sql req (Model.latest_successful_build_uuid build.job_id) >|= fun latest_uuid ->
+         (readme, build, artifacts, same_input_same_output, different_input_same_output, same_input_different_output, latest_uuid))
     |> if_error "Error getting job build"
       ~log:(fun e -> Log.warn (fun m -> m "Error getting job build: %a" pp_error e))
-    >>= fun (readme, build, artifacts, other_builds, latest_uuid, previous_build) ->
-    Views.job_build job_name readme build artifacts other_builds latest_uuid previous_build
+    >>= fun (readme, build, artifacts, same_input_same_output, different_input_same_output, same_input_different_output, latest_uuid) ->
+    Views.job_build job_name readme build artifacts same_input_same_output different_input_same_output same_input_different_output latest_uuid
     |> string_of_html |> Dream.html |> Lwt_result.ok
   in
 
diff --git a/lib/model.ml b/lib/model.ml
index ea4db3e..506061f 100644
--- a/lib/model.ml
+++ b/lib/model.ml
@@ -70,8 +70,29 @@ let previous_successful_build id (module Db : CONN) =
   Db.find_opt Builder_db.Build.get_previous_successful id >|=
   Option.map (fun (_id, meta) -> meta)
 
-let builds_with_same_main_binary id (module Db : CONN) =
-  Db.collect_list Builder_db.Build.get_other_builds_with_same_output id
+let builds_with_different_input_and_same_main_binary id (module Db : CONN) =
+  Db.collect_list Builder_db.Build.get_different_input_same_output_input_ids id >>= fun ids ->
+  Lwt_list.fold_left_s (fun acc input_id ->
+     match acc with
+     | Error _ as e -> Lwt.return e
+     | Ok metas ->
+       Db.find Builder_db.Build.get_one_by_input_id input_id >>= fun build ->
+       Lwt.return (Ok (build :: metas)))
+   (Ok []) ids
+
+let builds_with_same_input_and_same_main_binary id (module Db : CONN) =
+  Db.collect_list Builder_db.Build.get_same_input_same_output_builds id
+
+let builds_with_same_input_and_different_main_binary id (module Db : CONN) =
+  Db.collect_list Builder_db.Build.get_same_input_different_output_hashes id >>= fun hashes ->
+  Lwt_list.fold_left_s (fun acc hash ->
+     match acc with
+     | Error _ as e -> Lwt.return e
+     | Ok metas ->
+       Db.find Builder_db.Build.get_meta_by_hash hash >>= fun build ->
+       Lwt.return (Ok (build :: metas)))
+   (Ok []) hashes
+
 
 let job_id job_name (module Db : CONN) =
   Db.find_opt Builder_db.Job.get_id_by_name job_name
@@ -85,8 +106,19 @@ let job_and_readme job (module Db : CONN) =
   job_id job (module Db) >>= not_found >>= fun job_id ->
   Db.find Builder_db.Tag.get_id_by_name "readme.md" >>= fun readme_id ->
   Db.find_opt Builder_db.Job_tag.get_value (readme_id, job_id) >>= fun readme ->
-  Db.collect_list Builder_db.Build.get_all_meta job_id >|= fun builds ->
-  readme, List.map (fun (_id, meta, main_binary) -> (meta, main_binary)) builds
+  Db.find_opt Builder_db.Build.get_latest_failed job_id >>= fun failed ->
+  Db.collect_list Builder_db.Build.get_all_artifact_sha job_id >>= fun sha ->
+  Lwt_list.fold_left_s (fun acc hash ->
+     match acc with
+     | Error _ as e -> Lwt.return e
+     | Ok (fail, metas) ->
+       Db.find Builder_db.Build.get_meta_and_artifact_by_hash hash >|= fun (meta, file) ->
+       match fail with
+       | Some f when Ptime.is_later ~than:meta.Builder_db.Build.Meta.start f.Builder_db.Build.Meta.start -> None, (meta, file) :: (f, None) :: metas
+       | x -> x, (meta, file) :: metas)
+    (Ok (failed, [])) sha >|= fun (x, builds) ->
+  let builds = match x with None -> builds | Some f -> (f, None) :: builds in
+  readme, List.rev builds
 
 let jobs (module Db : CONN) =
   Db.collect_list Builder_db.Job.get_all ()
@@ -286,9 +318,9 @@ let add_build
     Db.exec Tag.try_add readme_tag >>= fun () ->
     Db.find Tag.get_id_by_name readme_tag >>= fun readme_id ->
     let input_id = compute_input_id artifacts in
-    Db.exec Build.add ({ Build.uuid; start; finish; result;
-                         console; script = job.Builder.script;
-                         main_binary = None; user_id; job_id }, input_id) >>= fun () ->
+    Db.exec Build.add { Build.uuid; start; finish; result;
+                        console; script = job.Builder.script;
+                        main_binary = None; input_id; user_id; job_id } >>= fun () ->
     Db.find last_insert_rowid () >>= fun id ->
     let sec_syn = infer_section_and_synopsis raw_artifacts in
     let add_or_update tag_id tag_value =
diff --git a/lib/model.mli b/lib/model.mli
index 1a45432..384c16d 100644
--- a/lib/model.mli
+++ b/lib/model.mli
@@ -39,7 +39,13 @@ val latest_successful_build_uuid : [`job] Builder_db.id -> Caqti_lwt.connection
 val previous_successful_build : [`build] Builder_db.id -> Caqti_lwt.connection ->
   (Builder_db.Build.Meta.t option, [> Caqti_error.call_or_retrieve ]) result Lwt.t
 
-val builds_with_same_main_binary : [`build] Builder_db.id -> Caqti_lwt.connection ->
+val builds_with_different_input_and_same_main_binary : [`build] Builder_db.id -> Caqti_lwt.connection ->
+  (Builder_db.Build.Meta.t list, [> Caqti_error.call_or_retrieve ]) result Lwt.t
+
+val builds_with_same_input_and_same_main_binary : [`build] Builder_db.id -> Caqti_lwt.connection ->
+  (Builder_db.Build.Meta.t list, [> Caqti_error.call_or_retrieve ]) result Lwt.t
+
+val builds_with_same_input_and_different_main_binary : [`build] Builder_db.id -> Caqti_lwt.connection ->
   (Builder_db.Build.Meta.t list, [> Caqti_error.call_or_retrieve ]) result Lwt.t
 
 val readme : string -> Caqti_lwt.connection ->
diff --git a/lib/views.ml b/lib/views.ml
index 71cffb9..7873fdb 100644
--- a/lib/views.ml
+++ b/lib/views.ml
@@ -194,9 +194,8 @@ let job_build
   readme
   { Builder_db.Build.uuid; start; finish; result; console; script; _ }
   artifacts
-  other_builds
+  same_input_same_output different_input_same_output same_input_different_output
   latest_uuid
-  previous_build
   =
   let delta = Ptime.diff finish start in
   let successful_build = match result with Builder.Exited 0 -> true | _ -> false in
@@ -214,8 +213,15 @@ let job_build
       h2 ~a:[a_id "build"] [txtf "Build %a" pp_ptime start];
       a ~a:[a_href "#readme"] [txt "Back to readme"];
       p [txtf "Build took %a." Ptime.Span.pp delta ];
-      p [txtf "Execution result: %a." Builder.pp_execution_result result];
-      h3 [txt "Compare with other builds"];
+      p [txtf "Execution result: %a." Builder.pp_execution_result result]; ] @
+      (match same_input_same_output with [] -> [] | xs -> [
+         h3 [ txt "Reproduced by builds"] ;
+         p (List.concat_map (fun { Builder_db.Build.Meta.start ; uuid ; _ } ->
+             [ a ~a:[Fmt.kstr a_href "/job/%s/build/%a" name Uuidm.pp uuid]
+                [txtf "%a" pp_ptime start] ;
+               txt ", " ])
+         xs) ] ) @ [
+      h3 [txt "Comparisons with other builds"];
       p
         ((match latest_uuid with
           | Some latest_uuid when successful_build && not (Uuidm.equal latest_uuid uuid) ->
@@ -223,18 +229,19 @@ let job_build
                       Uuidm.pp uuid Uuidm.pp latest_uuid]
                 [txt "With latest build"] ; br () ]
           | _ -> []) @
-          (match previous_build with
-           | Some previous_build when successful_build ->
+         List.concat_map (fun { Builder_db.Build.Meta.start = other_start ; uuid = other_uuid ; _ } ->
+             let fst, snd = if Ptime.is_later ~than:start other_start then uuid, other_uuid else other_uuid, uuid in
              [ a ~a:[Fmt.kstr a_href "/compare/%a/%a/opam-switch"
-                     Uuidm.pp previous_build.Builder_db.Build.Meta.uuid Uuidm.pp uuid]
-                [txt "With previous build"] ; br () ]
-           | _ -> []) @
-         List.concat_map (fun { Builder_db.Build.Meta.start ; uuid = other_uuid ; _ } ->
+                     Uuidm.pp fst Uuidm.pp snd]
+                [txtf "With build %a (output is identical binary)" pp_ptime other_start] ; br () ])
+           different_input_same_output @
+         List.concat_map (fun { Builder_db.Build.Meta.start = other_start ; uuid = other_uuid ; _ } ->
+             let fst, snd = if Ptime.is_later ~than:start other_start then uuid, other_uuid else other_uuid, uuid in
              [ a ~a:[Fmt.kstr a_href "/compare/%a/%a/opam-switch"
-                     Uuidm.pp other_uuid Uuidm.pp uuid]
-                [txtf "With build %a (output is identical binary)" pp_ptime start] ; br () ])
-           other_builds);
-      h3 [txt "Digests of build artifacts"];
+                     Uuidm.pp fst Uuidm.pp snd]
+                [txtf "With build %a (same input, different output)" pp_ptime other_start] ; br () ])
+           same_input_different_output);
+      h3 [txt "Build artifacts"];
       dl (List.concat_map
             (fun { Builder_db.filepath; localpath=_; sha256; size } ->
                let (`Hex sha256_hex) = Hex.of_cstruct sha256 in
diff --git a/test/builder_db.ml b/test/builder_db.ml
index 8bf0ecd..05ca48c 100644
--- a/test/builder_db.ml
+++ b/test/builder_db.ml
@@ -160,8 +160,8 @@ let add_test_build user_id (module Db : CONN) =
     Db.start () >>= fun () ->
     Db.exec Job.try_add job_name >>= fun () ->
     Db.find_opt Job.get_id_by_name job_name >>= fail_if_none >>= fun job_id ->
-    Db.exec Build.add ({ Build.uuid; start; finish; result; console; script;
-                         main_binary = None; user_id; job_id }, None) >>= fun () ->
+    Db.exec Build.add { Build.uuid; start; finish; result; console; script;
+                        main_binary = None; input_id = None; user_id; job_id } >>= fun () ->
     Db.find last_insert_rowid () >>= fun id ->
     Db.exec Build_artifact.add (main_binary, id) >>= fun () ->
     Db.find last_insert_rowid () >>= fun main_binary_id ->
@@ -228,8 +228,8 @@ let add_second_build (module Db : CONN) =
   Db.find_opt User.get_user username >>= fail_if_none >>= fun (user_id, _) ->
   Db.start () >>= fun () ->
   Db.find_opt Job.get_id_by_name job_name >>= fail_if_none >>= fun job_id ->
-  Db.exec Build.add ({ Build.uuid; start; finish; result; console; script;
-                      main_binary = None; user_id; job_id; }, None) >>= fun () ->
+  Db.exec Build.add { Build.uuid; start; finish; result; console; script;
+                     main_binary = None; input_id = None; user_id; job_id; } >>= fun () ->
   Db.find last_insert_rowid () >>= fun id ->
   Db.exec Build_artifact.add (main_binary, id) >>= fun () ->
   Db.find last_insert_rowid () >>= fun main_binary_id ->