That said, I do empathize with you. Jumping onto someone else's upload is bad behavior and poor netiquette. It is unfortunate that it happened to you, and I hope the bad experience does not make you stop visiting the site. It happens sometimes, but not all the time. And at the moment, there is no rule against it as it would be almost impossible (?) to police and track.
It could be completely accidental.
I have a lot of videos and I cant keep track of everything I have when I'm going through torrent pages. Many times I end up with several versions of the same video and I'm sure that at some point I have done what's discussed here.