There have been a few times where I have come across a question with a wrong or incomplete answer, provided a correct answer and then had the original answerer edit/correct/expand their answer to match mine.
If this is done quickly enough the stolen answer often gets the up-votes (it was answered earlier) and sometimes is marked as the correct answer (which at that point, it is).
I am not against people correcting wrong answers (especially little mistakes) or making some revisions. Nor am I against the idea of up-voting multiple correct answers - although I rarely do it when there are duplicate answers, I just up-vote the one that got there first.
All that to say, what is the general etiquette when you have had your answer stolen? I could leave a comment but that would tend to make me look like a petty jerk. I could down-vote the answer, but the answer is now correct so I'm really down-voting the user which may feel good to me, but be misleading to other users. Or I could just suck it up, be irritated, delete my "duplicate" answer and move on - this seems like the most mature, if least satisfying, response.
Perhaps there is a middle ground or precedent that I am unaware of for these types of situations?