I've rebought and advocated the purchase of Metroid Prime Trilogy (despite having that limited run disc), Metroid Fusion, Super Metroid, and Metroid: Zero Mission, (despite having working carts for all three) on the Wii U then dumped over a dozen hours into each title, to tell Nintendo they need to come back to the franchise. (The first two titles were bought before the reveal of that spin off.) On that note, I got Metroid Prime Trilogy when it came out in 2009 to play the first two Primes with Wii controls. So, I basically have 3 copies of Prime 1 & 2, and 3 copies of OG Metroid (unlocked in Prime 1 and Zero Mission).
After getting an SD card to MS Pro Duo adapter, I rebought some PSone classics (FF7, FF9, Crash Bandicoot 2, Crash 3, the Spryro Trilogy and Jet Moto), all to play on my PSP. [small]Funny how high memory prices stop people from giving you money, eh Sony.[/small] Now to list form!:
Chrono Trigger: Originally only had the laggy PS1 version included in FF: Chronicles, DS version to the rescue
Guacamelee!: own both Gold Edition and Super Turbo Championship Edition on Steam (at least STCE was $3 for Gold Edition owners when I got it) - STCE adds two new areas, new enemies, a new boss, and gives a little more backstory to a character.
Shantae and the Pirates Curse: 3DS, Wii U, and PC versions. It was pretty much to show support, since I missed the Kickstarter for 1/2 Genie Hero. (Granted, I waited for discounts on the second two versions.)
Genesis/Mega Drive Sonics: Sonic Mega Collection for Gamecube - As much as I love old school Sonic, the Gen and 'cube still work, so I'm not rebuying the games over again until they do a Taxman remaster of S3&K. I also have a Genesis cart with Sonic 1 & 2 slapped together with Robotnic's Mean Bean Machine (read: Puyo Puyo clone with bizarre robots)
Sonic Adventure 1 & 2: Dreamcast asploded. Traded in all games. (Stupid move but I was ~13.) Skipped the GC versions and finally went back to the games with the PC versions about when the HD console versions hit PSN/Xbox Live
Jak 1 & 2: Got the Jak Collection, mostly to try Jak 3. Still pissed Jak X wasn't included or offered as a separate (cheaper) title.
Legend of Zelda: Minnish Cap, Wii U VC
Ocarina of Time and Majora's Mask: got the 3DS remakes
Wind Waker and Twilight Princess: HD Wii U versions. For TP, I own the rarer GC disc, but played the Wii waggle-fest twice over between renting and borrowing it.
FFX HD: got it for proper widescreen support and one day I'll finally face Penance (that super hard ultra-boss)
ES4: Oblivion: gave the 360 copy to a friend, bought the PC (Hello, console commands!) GOTY version on data Frisbee, and later got the Steam version in a big Bethesda bundle
Fallout 3: traded in the PS3 version, got the GFWL version (I know, I know [small]It's one of the less bug ridden GFWL titles.[/small]) and finally the Steam version from the same Bethesda sale