Hi,
Not really. It depends what you mean by fighting. Has there been blood?
If it has got to that stage then they need to be separated. Some boars (males) just can't get on because they're both dominant (there has to be one dominant one in any piggy relationship really). If neither of them wants to be the submissive one, then you've got an issue.
With our two, it took about 4 months for the problems to begin (in terms of their age I mean). Then they just scrapped non-stop. Now they each have a cage and are amicable neighbours but that's the extent of it.