diff --git a/lcl/lresources.pp b/lcl/lresources.pp
index e639aa3d7b..02863b944c 100644
--- a/lcl/lresources.pp
+++ b/lcl/lresources.pp
@@ -1498,6 +1498,10 @@ begin
 end;
 
 procedure TLResourceList.Sort;
+var
+  i: Integer;
+  r1: TLResource;
+  r2: TLResource;
 begin
   if FSortedCount = FList.Count then
     exit;
@@ -1507,6 +1511,14 @@ begin
   // merge both
   Merge(FList, FMergeList, 0, FSortedCount, FList.Count - 1);
   FSortedCount := FList.Count;
+  // check for doubles
+  for i:=0 to FList.Count-2 do
+  begin
+    r1:=TLResource(FList[i]);
+    r2:=TLResource(FList[i+1]);
+    if (AnsiCompareText(r1.Name,r2.Name)=0) and (r1.ValueType=r2.ValueType) then
+      DebugLn(['TLResourceList.Sort ',i,' DUPLICATE RESOURCE FOUND: ',r1.Name,':',r1.ValueType]);
+  end;
 end;
 
 procedure TLResourceList.MergeSort(List, MergeList: TList; Pos1, Pos2: integer);