Hello and welcome to the forum!
I have three boars, so i know quite a bit on boar behaviour to help you Firstly I'd suggest reading through this, its a very helpful and informative thread for new owners to boars will explain everything for you on boar behaviour.
http://theguineapigforum.co.uk/showthread.php?t=28949
Boars go through their hormonal months between six weeks to 14 months, this can be a tricky time when they test out whose top pig, and this time is usually when fall outs occur.
I always suggest to let boars test out their dominance through rumble strutting/teeth chattering/ nose offs/chasing/ humping etc. this is normal, and depending on the boar is can last a couple of minutes to an everyday activity for some boys!
How big is your cage/hutch? If you can try to make it as big as possible. Boars need space, and its best to give them the most you can afford or provide. I'd also suggest providing two (or three if you can) food bowls/ hideys/ hay racks/bottles/ feeding areas (say two hay racks/trays at either end of your cage or hutch) so they can have alone time as well as giving them their own area to eat or drink/ relax.
If you do place hideys in the cage for them, try to find a hidey with two (or three) exits for the time being, so one boar doesnt become bullied into a corner. I find those free cardboard boxes you get from supermarkets work best as you can create a few exits in them.
Oh and lots of hay is a must for boars, try to keep them occupied. Place hay in toilet roll tubes (on the floor of the hutch/cage or hang them on a rope across the cage so they have to reach up to grab the stands of hay), place it in chubes/hideys/plant pots anything you can think of to keep them occupied.
I'd also suggest scattering veggies at feeding time so they aren’t arguing over a pile, and instead foraging for their food.
Another idea is to give them a bonding bath, so they smell the same and have the same group sent. If you do bathe them dont forget to wash everything down in the cage/hutch include. toys/hideys and food bowls.
If you do find that one boar is constantly humping/aggravating the other you can put a mesh divider in the cage/hutch to they are separate but can still see/hear one another just to let them cool down and have a break from one another.
However, if at anytime blood has been drawn I'd advise to separate them immediately, and you can try and bond them again once the hormonal period is over.
Hope this helps if you have any more questions dont hesitate to ask
Laura x
