First game I bought twice was Diablo 2. At the time I didn't know there was an expansion, so when I saw a copy of D2 and the expansion with a strategy guide for 12 bucks at a Goodwill, I couldn't resist.
I also bought FF7 from the PSN store. I have the original black label copy, but the first disk got loose and when I opened the case, it got stuck in the hinge and put a fairly substantial scratch in it. It only affects the part of the game after the world's most popular spoiler. When the prompt for disk two came up, I'd have to put that in, go to the next room and wait for it to load and then put in disk one. Later, after finishing the zone, I'd put in disk 2 and continue. The digital copy let me play without switching.
I also bought FF6 through the FF5/6 bundle even though I have it for SNES. But my SNES doesn't work.
And I bought two copies of City of Heroes to have two accounts. Godspeed, CoH. For truly, with your passing, you will finally have "Gone to the Americans" (inside CoH Joke)