I buy the Japanese copies of albums mainly because they come with extra tracks and another reason is because they come with OBI strips, which all Japanese CD's have, they're like little strips that go around the left of the CD and advertise stuff about the singer or about the album and I just love them lol I don't know why I have a strange obsession with them I think they look cool.
But the main reason is that I've bought the album when it came out, and then discovered that the same album in Japan has extra songs/remixes so I've wanted those as well to get the full experience of the album, so I then end up with more than one copy for some albums.
And wow I had no idea BOMT had 11 covers!
EDIT - OMG I just realised I missed out two of my singles for the collection photo, 3 and Someday! NOOOOOOOOOOOOO