In this question, Joseph writes "In general, we've agreed not to delete or merge duplicate questions."
Why is that, when was this agreement reached, and do we still follow that?
As a side question, is there a waiting time after a question is closed before the delete link appears?
IMHO in the case 100% identical questions, i.e. accidental double posts maybe in connection with a migration from SO, one should be deleted. If one of them has already comments and/or questions it should stay and the other one should be deleted. I don't think there is a reason for not deleting it.
If both have already non-trivial comments and answers a merge would be adequate.
As a rule of thumb I'd say: If it's an exact duplicate (or a follow-up) of the same user, then it's good to delete to keep our site tidy. If it's a different user, don't delete; at the moment, I can't think of a delete reason in this case.
A waiting time between closing the exact duplicate and removing is good. Once the question has been closed, it's protected and pointing to the right place. The questioner is still able to read the comments to the closed question for understanding.
I don't see harm in letting a closed question still remain some time for the benefit that the questioner and involved commentators are still able to see it.
The question which prompted the meta question was an extended duplicate with a clearer meaning than the original before it's been closed. I had copied the additional explanation to the original question. I planned to delete the (now exact) duplicate.
Edit: Now I've deleted the concerned duplicate--finishing work before the mod pro tem time ends in some hours.
