My two girls fought a lot and it was a terrifying experience each time.
A fight started because of food, so they ate separately.
A fight started over toys, so we took away the toys unless they were one on one with us.
A fight started over a treat, so they only got treats in their crates.
Then the fights started happening while one was simply walking by the other one. The fights got to the point where they couldn't be out at the same time. Thalia and Cache are both family members (Thalia is my dog and Cache is my boyfriend's dog). Both of us refuse to get rid of our dogs.
We worked with dog trainers and nothing stopped them from fighting.
It got to the point where if one was in their crate and the other walked by, a fight would still break out and they'd be trying to fight through the metal crate bars.
So, we turned to the crate and rotate method and WE LOVE IT. Thalia and Cache rotate time out of the crate with us. Cache is in her crate resting for 2-3 hours while Thalia is out. During that time, I work with Thalia on her obedience, we run in the back yard, we play ball, we cuddle on the couch etc... By the time it's her turn to go into the crate, she's pooped and ready for a nap anyways! Thalia goes in, Cache comes out and we do the same with Cache. The girls rotate nights getting to sleep in bed with us (Last night was Cache's night, so tonight Thalia will sleep in bed). They both eat separately in their crates.
It took us a little while to get used to, but oh my god, the peace of mind is incredible. I thought it would be mean to be forcing the dogs to stay in their crates, but they honestly have such a busy time out of their crate, that they just take naps in their crates and it's no different from them snoozing on the couch.
I think my example might be a bit on the extreme side in terms of the intensity and frequency of the fights that our girls got into, but the crate and rotate method might be a viable option if you want to keep both your pups?