Usually they would put it in the description that it is "also known as".

But what about a game with the same name but significant gameplay differences?  Such as "The End" where the Konami and Stern versions play differently.  Or a game like Real Ghostbusters where the Japanese version is completely different due to localization and gameplay changes.

I have reviewed all the comments.

While there is no clear cut format per say (for example, I know that there is one entry that says Gaplus/Galaga 3) I generally like to keep the two titles separate and mention that one is a copy of the other. 

If there are multiple games with the same name (like Batman or Avengers) there's not much I can do about it except ask that you pay attention to the company that made it and the year it came out.  Most often these will be different.  Ghostlord and I do our best to include screenshots and detailed descriptions. 

I do not differentiate between 2 player and 4 player versions of a game.  That's what cabinet style and number of simultaneous players are for.  If you have a generic X-Men cabinet with four players, I'll say it's an upright cabinet with four players simultaneous.  If it is the larger, more desirable cabinet, I will say the cabinet is a deluxe upright with six players simultaneous.  In both cases, the same X-Men listing will appear.

Good question.  Thanx

So, in the case of TMNT, an addition to the description should read, "aka Teenage Mutant Hero Turtles (2P)" Correct?

Please note -- There is a one word change - from Ninja to Hero, due to the ban of the word Ninja in the UK in the '80s & '90s.