Prior to February 2013, the duplicate close reason notice used to have the following wording:
This question covers exactly the same content as earlier questions on this topic; its answers may be merged with another identical question.
This wording was removed in February 2013.
This doesn't seem like correct behavior, because:
When questions closed as duplicates prior to the above change show up in the queue, I've always seen them have the newer wording in the reason box:
This question has been asked before and already has an answer.
Also, this question was closed in March 2013, after the changes linked above. The newer-style automatic duplicate notice, rather than the old Community user edit, shows the duplicate target.
Why does this specific question show an old close reason in the dialog?
It seems that it's because it's a newer-style closure but the reason ID is somehow 1, not 101. Why is that?