It's only natural for a collector to seek out every version of something they like. For me:
Super Mario Bros.: black box, w/Duck Hunt, w/DH&WCTM, SMB DX, 3DS eShop, All-Stars (Wii)
Super Mario Bros. 3: NES (x2), Famicom, GBA, Virtual Console Wii & WiiU
Yoshi's Island: SNES (x2), SFC, GBA
Bubble Bobble: NES, FDS, GB, GBA
Legend of Zelda: NES (x2), FDS, 3DS eShop, GC Collector's Edition
Super Mario 64: NA, JPN, JPN(Rumble ver.), DS, DS(JPN), official soundtrack
Zelda OoT: NA, JPN, 3DS, GC Collector's Edition
Those are just the big offenders I can think of.