until they are the right age and size to breed it is not a good idea to put them in the same viv, they probably fight as they are both competing for the same good spots within the viv
2.0 Normal Royal Pythons - Q and Little One 1.0 Chihauhaun Mountain Kingsnake - Simba
In addittion to what Hannah said... you may end up with just one, or even no snakes.... just not worth it! Snakes need to be introduced to each other very carefully indeed, and unless same size and both ready for breeding, may well not get on at all.
Or is there any chance that what you perceive as fighting could be something else?? My missus thinks my snakes fight, but cannot understand that they aren't fighting.