Some files get two or more torrents created for them,
even though the downloaded file has the same CRC value.
This is a big problem with hash-value-p2p setups, but
it could be fixed.
Since the .torrent file has the CRC value in it, it
seems logical that all torrent download programs should
check to see if they are already downloading a file
with the same CRC, and then either
a) don't download the new one, or
b) even better, cross trackers and dl/ul to and from