hey there,
I have ALWAYS had boars and never had any issues. I just happened to pick two i liked the look of, many years ago and was surprised when I started hearing stories of boars fighting afterwards as I hadn't had any issues.
I've had brothers, non siblings from the same breeder and also introduced a another boar into the home after one had passed away.
Space is definately key. You'll probably find they only snuggle up together if its cold, mine generally like their own boxes or hidey places so they have their own place to go. There's normally one that will be just that bit more dominant than the other which normal, its just them establishing who's boss lol. I would only seperate them if there was blood loss or severe attacking.
I had a pair once, Charles was always the more placid one and would let Dibbs be the alpha male but occaisonally, you'd see Charles sidle over to Dibbs and really sneakily nip the edge of his ear then turn around as if to say 'who me?' looking all innocent lol! Payback for being bossed all day long!
The most mine ever do is nip an ear or do the teeth chattering thing and then it's over, normally a food based argument! As guinea pigs are very social as long as there is plenty of space i think they prefer the company. The odd scrap is normal, especially when they're young but as I said, as long as its not severe attacking and not continually its nothing to worry about.
Sorry for the waffle, its just a myth I'm keen to dispel! Enjoy your boys x