diff --git a/cli/sheet.sh b/cli/sheet.sh
index 373bfe517..d633fefcd 100644
--- a/cli/sheet.sh
+++ b/cli/sheet.sh
@@ -1,5 +1,5 @@
 #! /bin/bash
-# Copyright (C) 2019 Igara Studio S.A.
+# Copyright (C) 2019-2020 Igara Studio S.A.
 
 # $1 = first sprite sheet json file
 # $2 = second sprite sheet json file
@@ -243,3 +243,32 @@ for type in horizontal vertical rows columns ; do
 		  -script scripts/compare_sprite_sheets.lua || exit $?
     done
 done
+
+# "Trim Cels" (-trim) with -merge-duplicates didn't generate the
+# correct "spriteSourceSize" for each frame.
+# https://igarastudio.zendesk.com/agent/tickets/407
+d=$t/ticket-407
+for layer in a b ; do
+    $ASEPRITE -b -layer "$layer" "sprites/point4frames.aseprite" \
+	      -trim \
+	      -data "$d/data1-$layer.json" \
+	      -format json-array -sheet "$d/sheet1-$layer.png" || exit 1
+    $ASEPRITE -b -layer "$layer" "sprites/point4frames.aseprite" \
+	      -trim -merge-duplicates \
+	      -data "$d/data2-$layer.json" \
+	      -format json-array -sheet "$d/sheet2-$layer.png" || exit 1
+    cat >$d/compare.lua <<EOF
+local json = dofile('third_party/json/json.lua')
+local data1 = json.decode(io.open('$d/data1-$layer.json'):read('a'))
+local data2 = json.decode(io.open('$d/data2-$layer.json'):read('a'))
+for i = 1,4 do
+    local a = data1.frames[i].spriteSourceSize
+    local b = data2.frames[i].spriteSourceSize
+    assert(a.x == b.x)
+    assert(a.y == b.y)
+    assert(a.w == b.w)
+    assert(a.h == b.h)
+end
+EOF
+    $ASEPRITE -b -script "$d/compare.lua" || exit 1
+done
diff --git a/sprites/README.md b/sprites/README.md
index 98e3f8267..8e45671a5 100644
--- a/sprites/README.md
+++ b/sprites/README.md
@@ -15,3 +15,7 @@
 * `tags3.aseprite`: 3 tags ("forward", "reverse", "pingpong") and 3
   layers ("a", "b", "c"), 4x4, several linked cels + layer "c" with
   empty cels.
+* `point4frames.aseprite`: Indexed, 4 frames, 2 layers, same cel
+  content but different positions, can be used to test
+  `-merge-duplicates` to check if all cels go to the same sprite sheet
+  position.
diff --git a/sprites/point4frames.aseprite b/sprites/point4frames.aseprite
new file mode 100644
index 000000000..a888f1734
Binary files /dev/null and b/sprites/point4frames.aseprite differ