User posts two answers, what's the best course of action?

Question

Reference question: CSS selector code last element

I don't know how long it will last (update: he edited his older answer) but this user "Nathan Lee" posts two answers.

First he posts a generic solution that aids the OP but isn't adapted to the specific code in the question. A couple of minutes later he posts another answer that looks very similar, but is directly adapted for the code of the question.

I wanted to downvote his older answer which I previously upvoted, but that vote is locked. I left a comment on his newer answer that he should remove his older, because what he is doing is bad. What should I do more? Which of the two answers should I flag, if that is necessary?

Answer 1

Okay, but suppose he did not: what should I do?

Flag it for moderator attention, and point out that the answer is a duplicate of one he had already posted on the same question.

It's no big deal, it looks like it is a simple mistake, nothing more - it is unlikely that he would have left it there (unless he was new and had no idea how to remove it).