Should answers on questions that already have a good answer be downvoted?

Question

A lot of people tend to answer questions after a good answer has been posted, should they be downvoted? Or should I just leave a comment?

Comments

You should comment telling them that there is no need so they don't do it in the future rather than down-vote them, unless it is actually incorrect information.
Than you can always flag it if it actually breaks the rules so it can be hidden easier.

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That's what I have been doing, I just wanted to make sure I was doing things right. Thanks :)

Answer 1

It is a rule that you shouldn't add an answer to an old question, unless you can add more information, write a much better answer, or the current answer(s) are wrong or out of date.

So if someone does that, the best thing to do is flag the answer and if a mod sees it or it gets enough flags, it will get hidden. Commenting is also helpful so the user knows what they did wrong.