Nevermind the smartass comment above...except for the links which have a ton of info in them...
The different sets are different dumps of the same game. Some are identical aside from perhaps the name of the "manufacturer", some have their difficulty tweaked a little, etc.
Basically if you want to eliminate all the different sets, create a gamelist with the CLONES removed. You can do this a number of different ways, in MALA you can create a gamelist minus clones in the gamelist editor I do believe (I am new with MALA so please forgive me).