Wiebke's questions are right... If you can tell us a bit more we might be able to give you more targeted advice but I can suggest that exchanging them is likely to cause at least as many problems.
I've just posted the same thing on another thread: the problem with choosing piggies from a pet store is that you just tend to pick two, that you like the look of, from a group. It's a bit like you picking your husband/wife from 15 photos then expecting to live in a bedsit for the next 50 years, without ever really leaving the house and get on perfectly without squabbles.... We wouldn't do it but we expect our piggies to. Good pairings or groups are all about personalities and who fits well with each other, that's one of the reasons we strongly advocate rescue as a place to get piggies because they come in well bonded pairs or groups with lots of support and back-up.
It sounds a bit like your piggies are really testing their boundaries and things are getting a bit heated. Regardless of what sex and age they are you can make sure you have the basics right like:
- Space - the more the better but a cage for a pair should be minimum 120cm x60cm. For boars particularly space is often crucial to them getting along
- Two of everything - hideys, food bowls, water bottles. Having two limits the chances of them fighting over the prime spots or food and makes sure the lower ranked pig doesn't get bullied out of their share
- Blood drawn - if you get to this point then it is possible you need to separate. I wouldn't always but I have enough experience of my boars to know when to leave them and when not to. Keep a dustpan handy to separate any fights so you don't get bitten by accident...
I am usually of the opinion that as long as one of them isn't getting bullied to the point there is health issues or a lot of distress, or a significant fight then I tend to leave them to sort it out themselves.
Your piggies are quite new to you so they've had a lot of change lately and will still be trying to sort out what's what and who's in charge. Hopefully they will calm down over time but also be ready in case they don't. If you have a local rescue (see our locator) they may also be able to offer practical advice.