I would have guessed Final Fantasy I (available for NES, PS1 in Final Fantasy Origins, GBA in Final Fantasy: Dawn of Souls, PSP, and Wii Virtual Console) and either Super Mario Bros. 1 or 3 (available for NES, SNES in Super Mario All-Stars, Game Boy Color/Game Boy Advance, and Wii Virtual Console). I also considered guessing Phantasy Star II (on Genesis, Wii Virtual Console, Game Boy Advance, PS2, and PSP), as well. I didn't know that there were so many different versions of Resident Evil II out there!
As for myself, I happen to own Final Fantasy VI on three separate systems, but that's not my record; I think I've bought (or my parents bought) Final Fantasy Legend II for the original Game Boy at least three times, because my brother and I lost it several times over the years. Also, if you count Pokemon Red/Blue/Yellow as one game, then I have three copies of that, too.
As for myself, I happen to own Final Fantasy VI on three separate systems, but that's not my record; I think I've bought (or my parents bought) Final Fantasy Legend II for the original Game Boy at least three times, because my brother and I lost it several times over the years. Also, if you count Pokemon Red/Blue/Yellow as one game, then I have three copies of that, too.