There are two types of variations with the Xonox cartridge molds. With Ghost Manor, and possibly with others if I can acquire and examine the backs, there is a size variation with the copyright information. As you can see in the photo below, the size of the 3 lines is smaller on the top version than the bottom. I'll try and confirm any other variations if I can in the future.
Some titles have two different mold colors, grey and black. Below is the example of Artillery Duel / Chuck Norris Superkicks. Again, since Xonox titles are not so easy to acquire, I will try and update any new information as I get it.