Borderlands, I have it for the pc but then my graphics card decided to die on me so I got the game for the 360 as well so I could play it without it looking like a 800x600 rendition of Lego Borderlands.
I also have around 3 copies of Worms Armageddon due to a destroyed disc thanks to a family member and some multi-buys, but you can never have enough Worms in your life so it's all good.