First find out if the two males are brothers - are they from the same litter.
You should only really house two males togther if they are brothers otherwise they will not get on together and will fight, and will then need separate cages/hutches.
I bought two brothers who still fought and well you cannot really predict this happening until it does. But I soon found that increasing there cage/hutch and run space stopped them fighting.
Also try supplying plenty off food and water so they dont fight over that even suppy two bowls and two water bottles if it helps them.
Also give each guniea pig the same treatment as they are not stupid animals and can get jealious.