I wanted to complain about the fact that when a shot from a famous movie is posted, you can find 3 or 4 shots from the same movie posted by other players no longer than a day after. I think there are like 4 shots of forrest gump and probably as much for Fight club in the new submissions section...
I think there should be a period of wait (like a week at least) before you can repost a shot from a movie that has just been uploaded.
That being said, as long as they are not dupes I dont see what the problem is. You can get very different looking shots from the same movie, and no rules are being broken.
If its a bad screenshot then you could always vote it down.
I think there was an idea to have a maximum of two shots from one movie in the new submissions. But they did not implement it because it would give hints (there are already two shots from your movie in the new submissions). (At least, this is all I remember about this issue)