lots of people have different views, like a lot say don't put a guinea pig with a rabbit which i agree with, they eat different food have different dietary requirements and a rabbit can get too big to live with a piggy, even the smallest breed Netherland dwarf is bigger than a piggy, so a kick from a large rabbit is dangerous.
Two male pigs can live together. In young days their male hormones are all over the place but they grow out of it. If it gets heated put a temporary divider in the cage if possible if it makes you feel happy and shy piggy will come to less harm. But the best ideas are if they fight over food and water and hay supply two bowls of food, two water bottles, two piles of hay= end of fighting it works with mine, now they have grown up they are happy sharing, if they eat too hungry they will get agitated and fight so make sure they are well feed and watered.