As the others have said, there is not a limit of how many co-dominant morphs you can get in a single snake but the odds of hitting the larger numbers are greatly reduced. The other issue is like Debrah mentioned, once you get past 3 it becomes more and more difficult to identify exactly what morphs are actually in the snake. Not to mention it starts to become pointless because a lot of combinations start to become muddy and less attractive than a snake that may only have 2 or 3, at least in my opinion anyway.