hmmm i think they'll always do that until they really get ot know eachother.I have that problem with all my female hamsters but not any of my other animals.Whenever i put new food in they fight about it like thats the last food they'll ever get.Even though they stick all the food into 1 pile in all of their sleeping spots
.anyways if they just kinda rumble and not really fight it should be ok.i would think adding a third pig would be better since they wont team up on eachother and the squablin will be spread out over 3 .