Oh yes, but only if I love the game and feel the developers deserve my money so many times. The reasons vary, usually because a better or more "complete" version has come out, sometimes I simply have to "collect" and other times it's simply a replacement.
x2 Halo: CE - Xbox, PC and the anniversary edition.
x4 TES: Oblivion - Xbox 360, Xbox 360 GOTY, PC 5th anniversary edition, PC Steam
x2 Silent Hill - PS1 and PSN
x2 Silent Hill 2 - PS2 original and PS2 Director's cut
x2 Silent Hill 4 - Xbox and PS2
x2 Portal 2 - Steam and PS3
x2 Battle for Middle Earth - PC twice because I got rid of it then wished I hadn't
x2 Enslaved: Odyssey to the West - Xbox 360 twice because I got rid of it then wished I hadn't
x3 Mass Effect 2 - Xbox 360, PS3, Xbox 360 Collector's Edition
x2 Mass Effect 3 - Xbox 360, Xbox 360 Collector's Edition
x3 Metal Gear Solid 2 - PS2, PS2 Substance, PS3 HD Collection
x4 Metal Gear Solid 3 - PS2, PS2 Subsistance, PS3 HD Collection, Snake Eater 3DS