Sookeh Look at CAVY SPIRIT Guinea-Pig Social Life.
There;s a good article on there are lists Non Combative Combative and Fighting Behaviour.
The teeth chattering is a warning sign, but it doesn't advice seperating unless blood is drawn. I'd find it really hard to listen to my boars having a full-on fight (and when they did have a couple of months after we got them it was the smaller pig who was the aggressor)
Which one of your pigs is starting it all off? You'll find one is Alpha Pig and maybe the other is trying to overturn this ,so fights start.
Short term- have you got a water spray? You could give them a bath to make them smell 'neutral'
I gave mine a haybox each when they came in at night. Once they were ok (I did seperate them last winter at night, but this winter I've left them together). They will (mostly) happily share a haybox, there's the odd spat but they sort it.
We cuddle the boys in different rooms to give each other space until GP1 gets fretful and wants GP2 back.
How old are they? My boys started getting a bit narky with each other around the 6-9 months age.
I think it depends on how physical they get. Can you tire them out with a big run so they don't have the energy to fight? Or I used to distract mine with a treat when they started - they can't argue with their mouths full. If they were really bad I would take one out of the cage for a few minutes. Having 2 houses for them helps, so they can hide from each other - I arranged mine so that they couldn't see each other when they were inside them.
I mainly left mine to it and they get on okay now. Smoothpig is missing a small bit of ear which I think Scruffypig must have 'removed' in a fight. They were horrid to each other for a couple of weeks then settled down again. They are just deciding who is 'Top Pig' - once they've worked it out, they should be fine. I helped mine out a little by feeding Smoothpig first (he's Top Pig in our house) to preserve hierarchy.
My two boars have been settled together for months now. My previous boar lost two of his previous pals and seemed to have settled with his new one. Today and last night though they've started doing the ready to fight teeth chattering noise whenever they're near each other. What should I do? Should I separate them? I really can't get any more so re matching them wouldn't be a possibility.