I think the problem is that you can not change your vote. When duplicate stories appear in the front page then you will probably upvote the first one. Problem

I think the problem is that you can not change your vote. When duplicate stories appear in the front page then you will probably upvote the first one. Problem is that this may not be the one with the highest score, or with the biggest discussion. When you then realize that there is a better submission of the same story, you can't change your initial vote. I think that if you could change your vote, the problem would be corrected by the community itself.