What's the process whereby a "duplicate" designation gets removed?

Question

Suppose some post has been marked as "[duplicate]".

Next, suppose that the author of the post edits the post, and thereby makes a sufficiently convincing case for why the post is not a duplicate after all.

Is this all the author needs to do in order to have the "[duplicate]" designation removed?¹

If not, what else must this author do in order for this to happen?

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^{1 The only way I can imagine this would be the case is if any post that had been edited by its author af some point after being marked "[duplicate]" would get automatically flagged to those with the authority to remove the "[duplicate]" designation. This arrangment seems to me implausible somehow, but for all I know, that may be what happens.}

Answer 1

The only way I can imagine this would be the case is if any post that had been edited by its author af some point after being marked "[duplicate]" would get automatically flagged to those with the authority to remove the "[duplicate]" designation.

That's exactly what happens; if anyone (the author or another user) edits the question within 5 days after the closure, it will automatically end up in the Reopen Votes review queue where those with 500 or more reputation can vote to reopen it (or to leave it closed, if they think it's still a duplicate).

This is explained in the Help Center:

Similarly, the reopen queue will contain any post that currently has an active reopen vote. Users can vote to reopen, edit the question (which includes a reopen vote), or leave the question closed. A certain number of Leave Closed votes will again kick the question out of the queue and begin the reopen vote aging process, and of course, another reopen vote will put it back into the queue. Questions which get edited within 5 days of being closed will automatically show up in the reopen queue for review.