If you are introducing two guinea pigs together for the first time - rather than bringing home siblings from the same litter - it should be done on neutral territory, rather than in a hutch that one or other of them has already come to see as its territory. There will usually be a certain amount of chasing around, squeaking, and teeth chattering. If the GPs are boars, there will be some rumbling growls as well. But it is very unlikely to end in combat!
These Peruvian guinea pigs should be the best of friends if introduced over dinner!
Provide lots of food in several different bowls, and piles of greens on the floor too. The guinea pigs are then likely to engage in their favorite activity of eating, and getting to know someone over dinner cuts through to the chase and avoids the need for face-offs!
If the enclosure has plenty of tubes and cardboard boxes to act as hideaways the pets should soon settle down together. If they seem to be getting on too well, it might be a good idea to check their sexes again, or ask someone experienced with guinea pigs to check for you!