Fernie Your boys have certainly hit their teens and will begin testing their hierarchy, plus they also have a lot of pent-up sexual energy that they don't know what to do with.
It is very normal for them to go through this stage - as Lord said, I've got (well, DD really) 5 boys (two are brothers and are 4 months older than the other three, who aren't brothers but have grown up together) so have experienced it twice when they hit the 6-8 month age. They all live together, bar one, and mostly without problems.
Of the five, there have been two problem piggies. In both cases it was the smallest ones that have become aggressive. For the older one, DD decided to have him neutered in case he couldn't get on with the others (especially his brother, who he gave a split lip), and instead of being a lone GP, he could live with a girl. He has now settled down completely, but it took 2+ months so wasn't due to a drop in testosterone.
With the other, he became very aggressive (mostly towards the neutered one), and was separated for a week, but after reintroduction he had a series of problems (overgrown teeth and a broken leg) that meant he had to be kept on cage rest and so was separated for about 10 weeks. Reintroduction hasn't happened yet, despite DD's best efforts, probably due to the fact he's no longer one of the group (he's not aggressive any more, just very wary and it unsettles the others and causes a great deal of tension, raised fur and teeth chattering), but if he hadn't have had to be separated for so long he may have been able to return without problem.
However, with the other three, there have been no problems at all. They occasionally bicker (usually over who's turn it is to lie in the middle of the hay pile!), but otherwise they all live together without issue. They are now 16 and 12 months old and have completely settled, and have been for a good 3-4 months.
I wish I could say for certain that they'll be fine, but I wouldn't want you to think they'll settle then they decide to have a giant fight and one (or both) get seriously injured. The posturing escalated very quickly (within a few days) to full blown fights with our boys, so I'd say if they've not had a proper fight by the weekend, you should be okay. They may continue to posture for another couple of months, but will almost certainly have settled by 9-10 months old.
Try and reduce conflict by giving them a hidey each, plus one extra, and a food bowl and water bottle each. Also, the more space they have to run around and burn off energy the better. It also seems that providing a distraction (such as a new handful of hay or some kale/dandelion/grass etc) helps to settle any posturing before it becomes a fight.
Best of luck!