Well, most people say that putting a female and male together is a bad idea and that it is usually only good to put them together for breeding. However, some say that their fish are fine after being put together(male+female). I guess it would depend on wether or not they are docile, the size of their territory(the bowl) and other such factors.
Though, one thing is for sure, Beta's are solitary fish. So, if you are afraid they will fight, it would be best to seperate them.