Suppose I have a closed challenge "Closed" and an old challenge "Old" and want to create a new challenge "New". Closed is closed as a duplicate of Old because entries from Old are competitive in Closed because Closed allows a super-set of entries from Old. Now all entries from New will be (likely?) competitive in Closed but 100% are banned in Old (that is, Old and New have an empty set-intersection and Closed is a super-set of New).
My question is now:
Would New be closed as dupe of Closed (or of Old) or would it be allowed to stay open?
To make this more interesting, the total textual non-fluff difference between Closed and New will be about two lines (out of 50 or so).
Note: This is intentionally abstract, but I bet you can figure the involved challenges out if you really want to ;)