A few minutes ago I flagged this question as a duplicate of an earlier one; when I came back to it, it showed as having been "marked as duplicate by Steven Stadnicki, Community". I've never seen the Community bot mark duplicates before; is this new behavior? What triggers it?
For ease of future reference I quote a part of the announcement New UI encourages askers to confirm or dispute duplicate votes below.
[T]he banner shown to askers whose questions have attracted at least one duplicate close vote has a couple of ... options:
If the author clicks the first button, they're shown a confirmation that clarifies the results of this action somewhat:
If they click "Ok", the question is instantly closed:
If, instead, they edit, they'll be offered this guidance:
...and once an edit is submitted the choice will go away until another duplicate close-vote is cast.