You may have to separate them
If you find that your Guinea Pigs are fighting to make sure that it's not just one ore two asserting dominance if you see that it's a problem would recommend separating them overnight.
If you have a double hutch, we will suggest you make a secluded sleeping area on the lower level. Make sure that this is big enough for your Guinea Pig to be completely hidden from view and has enough bedding.
You may need to bring one Guinea Pig in your house overnight and then reproduce them the next day.
They might size each other up, but hopefully, they will start to get along, if they persist repeat this 2-3 times and see cooler heads prevail.
You could use some small fencing or separators inside the run and hutch to segregate the Guinea Pigs, these can be found online and is relatively cheap.
If this persists, you may have to visit your local vet as this will be upsetting for your pets.
We have written a blog post on Guinea Pigs fighting that those into more detail and explores their reasons why this sometimes happen.
You can read our blog post by clicking here: http://homeandroost.co.uk/blog/why-guinea-pigs-fight/