This question already has an answer here:
When a question (probably with several answers) that was asked a long time ago gets bumped via an edit or another answer sometimes it is discovered that there are duplicate questions. In most cases the questions get closed very rapidly.
Take, for instance this question: Licensing System for .NET which was asked on Feb 27 2011. Yes, it did have duplicates which were pointed out within 5 minutes of asking. The question was not closed until today (Dec 20 2012) when someone bumped it.
Looking through the related/duplicate questions posted as comments to the question, I found that most of them are not closed.
My questions are, if all these other questions have been detected as duplicates then which of the questions should be closed?
a. Those that were asked at a later date?
b. The one with fewer answers?
c. The one which was just bumped?
d. Some other criteria?