I just came across a question that was closed a dupe, so I went to the original. It too was closed as a dupe of another question, so I went to that one. Fortunately, after a couple dupes, I finally found the real one.
Could we either disallow marking a question as a dupe to another question that is closed as a dupe? That, or automatically figure out the nearest non-closed question that appears in the sequence?
#1381842 (Closed) ->
#1040006 (Closed) ->
So in this case, when somebody tries to close the first by referencing the second, it bounces back as an invalid dupe-source, or it bounces back by marking the first as a dupe to the third.
Additionally, perhaps some type of process should be set in place to routinely merge dupes too.