Yesterday I flagged this question with "in need of a moderator intervention" because it was the third time the author asked the very same question.
The moderator handling my flag answered: "They should edit their post. You can vote or flag such posts as duplicates of the original post". However, as far as I know, casting a closing vote or raising a flag for a duplicate can only be done with a post that already has an answer. Did I miss something? Is it possible with a post without answer?