When a question is flagged/close-voted as duplicate by other users, the question asker has the possibility to unilaterally approve this vote and have the question closed. If this happens, the last close-vote is attributed to the Community user, instead of the asker.
This has occasionally led to confusion, and there is an old feature request, to list the asker as the last close-voter. I agree with that feature request, because it would definitely give more accurate information.
The only answer to the feature request says that "unilaterally approving a duplicate vote" and "casting a close vote" are different actions. This is true, as the asker has the option to just cast a non-binding close vote.
My question is, why do we have these two different actions? If the asker agrees with the proposed duplicate, why would they want to cast a non-binding vote instead of a binding vote?