I own Ocarina of Time on N64, Gamecube (both Collector's Edition, which also includes Majora's mask and Legend of Zelda 1 & 2, and the version with Masterquest that came with my copy of WindWaker). I also own a PC version of Fallout 3 as well as Xbox 360, also a copy of Resident Evil 4 on both Playstation 2 and Gamecube since I thought my copy on PS2 was stolen. Soul Calibur 2 on Gamecube and Playstation 2. Same reason. It's not so much I'm a fan of things to have more than one copy, mostly I mistrusted this kid that used to come round my house every now and again...