The first thing is to be clear that purring and wiggling their bums (called rumblestrutting), mounting, chasing and bum sniffing is not fighting. That is normal dominance.
An actual fight is unmistakable. There will be a rolling around furball of two piggies. Do not put your unprotected hands in the middle of piggies fighting like this. You will get hurt.
A new environment ie bringing them to your home will cause them to reestablish their relationship. This takes around two weeks. During this time you will an increase in dominance while they do this. In a well bonded and compatible pair this will amount to nothing more than dominance and they will settle down.
In an unstable pair, the change in environment can bring problems out.
You will also see an increase in dominance during their teens (4-14 months of age). Again, in a compatible pair it will not amount to anything.
The reality with boars is that you will see dominance behaviours in compatible boar pairs throughout their whole lives (they tend to mellow on old age though as testosterone fizzles out), it’s how they cement their relationship.
However in a pair who are not or who turn out not to be compatible (as can happen at any point particularly during their teens), then the dominance will become intense as one of the boars refuses to back down and can result in fighting. For a pair to work one needs to be dominant and one needs to be submissive. If they both want to be dominant then this is when a bond will break down and fighting occur.
If a fight happens the pair will need to be permanently separated and live side by side.
They are not reacting because you are female.
It would be helpful if you could tell us the measurements of the cage. Space really is important to a boar pair.
Do you have multiple hides?
Do all the hides have two doors in them?
Do you have multiple hay piles, water bottles etc?
Please do read the guides below. They detail boar pair behaviour
Bonds In Trouble
A Comprehensive Guide to Guinea Pig Boars
Boars: Teenage, Bullying, Fighting, Fall-outs And What Next?
Dominance Behaviours In Guinea Pigs