You have two teenagers who are hormonal and you will see changes in their relationship.
One needs to be dominant and the other submissive for their relationship to function. You should be seeing mounting, chasing and rumbling as it’s how boars form and maintain a relationship throughout life - it’s not anger at all.
What you don’t want to be seeing is actual fighting, injuries and bite wounds (i believe this can be slightly more tricky with skinnies given they don’t have any hair to protect them so a minor, accidental scratch can appear more than it actually is) or bullying (which is much more than just dominance - bullying is consistent aggressive behaviour which can/will see one piggy lose weight at each weekly weight check through never being allowed to eat, become withdrawn, hide a lot).
If the behaviour remains as and within normal dominance, then there is nothing for you to do - you don’t separate for dominance behaviour. It’s something they need to see through and it is something they will do lifelong as their e affirm their bond.
If there is actual fighting then that is immediate and permanent separation. If their bond is in trouble but not fully broken, then you can do a temporary separation to allow them to settle and then a neutral territory reintroduction to allow them to make up their minds about their relationship. The reintroduction will tell you fairly quickly if they actually want to be together or not.
Can you explain more about their set up please?
How big is their cage (measurements in cm)? Space is very important to boys!
Is there two of every item (bottles, hay piles etc) and do all hides have two exits?
The guides below will help you gauge their relationship.
A Comprehensive Guide to Guinea Pig Boars
Boars: Teenage, Bullying, Fighting, Fall-outs And What Next?
Dominance Behaviours In Guinea Pigs
Bonds In Trouble
I have a bonded 5 year old boar pair. They are older now so tend to just be more about companionship than dominance but still get a bit rumbly and still occasionally mount each other.
I also have two 7 month old boars. They were together as a pair initially but their bond broke down when they hit the teens at 4 months old. They launched in a full on fight one day seemingly out of the blue, and now have to live separated as neighbours.