I own 5 copies of The Legend of Zelda: Ocarina of Time. Ver. 1.0, 1.0 (gold cartridge), 1.1, 1.2, and the 1.2 Gamecube edition. Each revision has pretty significant differences, and it's fun to own every one for the sake of my video game collection.

As for pinball machines, I can see someone wanting a prototype along with a production version of a game, or perhaps multiple copies of a game if manufacturing specs changed between them, but otherwise for the average enthusiast, I don't really get people owning multiples of the same game. You just know there's some collector out there with a warehouse/garage full of of Twilight Zones or Addams Families doing absolutely nothing with them, but refuses to sell because of "reasons."