(will double space if it's hard to read)
-Beat Trine on PS3 and bought from steam.
-Bought Overlord series on PS3, then re-bought on steam for no reason (massive sale).
-Own 3 copies of Oblivion, xbox360 GOTY (and purchased all DLC aside from horse armor and spellbooks), Steam Ultimate edition, PS3 regular edition that will probably never be played.
-Sonic 1, 2, 3, & knuckles, own pretty much every version released other than the original cartridges and sonic jam (note: DO NOT GET ANY FROM XBLA, bad ports).
-Plan to get Galcon Labs PSN Mini while owning galcon fusion on steam.
-would get a copy of Eufloria from PSN if it was playable on PSP while owning it on Steam.
-have Borderlands on Xbox360 but don't want to pay for Gold anymore so I bought it on steam.
-Torchlight bought in a steam sale but didn't care for controls, fell in love with XBLA version.
-bought Beyond Good and Evil for PS2 about a 1-2 weeks before HD remake was announced, hope to get that instead of playing my PS2 copy.
-have Bionicle the game for PC and gamecube, I got the PC version first but have only beaten the Gamecube version
-bought Defense Grid: The Awakening off XBLA then ended up with a copy on steam when purchasing the indie strategy pack.
-plan to get the Jak and Daxter trilogy HD remake despite owning all 3 games (not immediately though).
-Got the PSP version of Little Big Planet despite owning and hating the PS3 version, was free due to PSN outage, but would have preferred nearly anything else. (haven't played PSP version yet so it may turn out to be decent)
-Bought megaman zero 3 and 4 for GBA then bought megaman zero collection for DS to get zero 1 and 2.
-rented metroid prime 2, bought metroid prime 3, bought metroid prime trilogy, bought metroid prime for under $5, and hope to own a copy of metroid prime 2 in the future.
-might get the updated-updated version of phantom brave for PSP rather than play my wii version any more.
-own pikmin 2 for gamecube and would love to get new play control for pikmin 1 and 2 on wii.
-own shadow of the colossus and bought ICO and shadow of the colossus collection for ICO.
-doesn't really count since they're different games and I bought them on the same day, but Sonic Colors Wii and DS.
-own Sonic Unleashed on xbox360 then got Sonic Unleashed wii as a Christmas present.
-have Zelda: Ocarina of time on wii virtual console and want to get 3DS remake once I get a 3DS (need a separate reason to get one though).
-have also bought Audiosurf and Sanctum on steam, then bought packs that included them.
-Tales of Vesperia is my favorite game on xbox360 and I WOULD DO ABSOLUTELY ANYTHING FOR AN ENGLISH COPY OF THE PS3 PORT!
[shocked silence] I honestly am completely surprised and kinda horrified by how many games I've re-bought!
(the red squigglies were invading my post, chrome didn't recognize most of the video game hardware and software names.)
(may return later to fix capitalization)
edit: I have not gotten rid of any of these games and still own each copy I bought.