Please don't breed them. There are so many homeless guinea pigs in rescues and shelters. It only takes a moment for guinea pigs to mate.
Your females could both be pregnant. Unfortunately guinea pig pregnancies have a high mortality rate--1 in 5 guinea pig pregnancies ends in death. Also unfortunately, your males will probably now try to fight each other because they will both want to be with a female, and now that they've been with females will only see the other male as a threat.
My advice is to move the males' cage far away from the females, so they don't even see each other. Make sure they have a large enough cage--pet store cages are too small. Check out the cage size standards at www.guineapigcages.com .
Anything smaller than 10.5 square feet and they are liable to injure each other. Don't ever put your hand in the cage when they are fighting. They have very sharp teeth and you could end up needing stitches.
It's best to try to separate them with a dustpan or even drop a towel on them. Let them cool down a bit before you attempt to pick them up. Oh, and just because they are brothers doesn't mean they will get along.
In any guinea pig pair one will be the dominant pig, and if they both want to be it they will fight until they get it figured out.
It is a power struggle, aybe they scent of female afar in heat. It is typical animal behaviour to impregnate and to beat off competition, has been with every species, incl. Humans since the dawn of era!
So maybe before they were all good as perhaps female wasnt ovulating, as they are rats with little common sense and aren't trained, they smell something instinctive and are fighting territory, try seperating all of them, clean cage out, and only put one at a time with female, so seperate totally whilst they act that way. Guaranteed she will have babies. But if that is not a desire, 2 males and 1 female is commen sense not the right arrangement, three's a crowd?
Just like any relationship. "if you **** with my mate, i'll kill you! , lol!
We may think they lack intellect, but battle of the sexes and territory is always inbeaded in every species. So leave them with their own mates from here on out, maybe eventually they can all live together, put don't think so! They know this by smell!
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.