It's very normal for this breed to have dog aggression. It's in their genetic make up, you can not train it out of them. However, it can be managed through training!
you will have to work with each dog on his focus. Search the forum in the training section about this...lots of great tips and tools.
Don't be upset at them, though I know it can be frustrating. Just like herding dogs have herding instincts, guarding dogs guard, hunting dogs hunt....dogs that were bred to fight will have that instinct. It's just the breed.
You could rehome one of them, but you could also do crate and rotate. A lot of us here have multiple dogs and they are crated and rotated. It's not big deal and fairly easy to get used to.