Yup. Duplicate answers. We have seen some of them in last few days. Like this, this, this, this and possibly many more which I didn't mention. They aren't exact duplicates but they still have the same main answer.
Every duplicate answer is not bad. Some of them might contain some extra information which might not be in the original answer. Instead of posting another answer I would prefer to just comment on the original answer to add that extra information but I guess those kinds of duplicates are still okay. But the other kind of duplicates which have which have poor quality or contain no extra information. What should we do about them? Should we flag them? If yes, what reason should we choose (spam?, not an answer?, low quality?)? If no, should we let them stay there and just start downvoting until (if) the answerer deletes them? What is the solution?
EDIT: I am addressing only those duplicate answers which are posted after hours or days and not those which are posted in the difference of some few minutes.