In reviewing questions in regard to closure or reopening, I voted to reopen a question (which had been closed for reasons other than duplication), because it seemed a reasonable question. Later, I realized that the question was a duplicate of an earlier question (which was open and upvoted and had received an upvoted and accepted answer). So I voted to close the later-posted question on that ground. Do my two votes stand, and so cancel each other? Or does my later vote supersede the earlier one?
(As it happened, more votes to close on the ground of duplication were received, and the question was closed for that reason.)