We lost 2 of our trophy fallow to them fighting in one week.

Man that's painful!

Sorry to hear that. We had that happen often than not on our ranch as well. That's why it's so hard to get really well mature fallow bucks to large size. Dominant males will fight continuously to exhaustion which will many times lead to death.
I have come up on males fighting so aggressively that you can get close and yell at them and they wont quit.
Feel your pain. Experienced that with them a lot.
Just when they get really mature and big antlers that always seemed to happen.
It's seems to be more prevalent in herds that have low numbers of does vs the bucks. That was the way it was for us.