For Bally and United, we believe that the items in the machine listings are an accurate list of all the games made. We are also fairly sure that the listings for the non-US manufacturers are incomplete.
Periodically, someone asks about a game that is not in the listings. It's almost always the case that we are dealing with an aftermarket backglass that for legal, moral, or boredom reasons someone decided to change the name of the game.
Game MasqueradingOne reason that rescreens were done with different names were to try and get around the local laws banning the machines. In some places, the machines were declared illegal by name, so if your machine wasn't on the list of illegal ones, you could operate it until someone got the machine added to the list. I assume getting the names added was a time-consuming legal process, so you could happily rake in the loot while the lawyers were grinding away.
Here's all the ones we've been told about, and if you have a different one, zap us a comment.