I do have all drakes! I have 2 pekins, and 2 runners. Runners were hatchmates, pekins are suspected to also to be together since hatching. Mine get along in the winter, and fight all summer. (Not sure if the runners will, I just got them in September. )
Water means sexy time for ducks! So they will fight in the pool. But not enough where I have to intervene. It's weird, the pekins will generally bathe first and then the runners, but not always. Everyone wants to use the pool at the same time. I usually fill up small seperate pools (cement mixing tubs) which helps.
Last summer my pekins faught terribly, and I had to seperate them with a small fence.
One was generally the aggressor so I'm hoping to pair them up or seperate my fiesty duck. I use small fences that I can step over, and they can see each other.
I think your other option is to rehome one, and get 3 girls for the remaining one, or get 6 or more girls and keep everyone.
Heres a clip of a brawl, before I knew what was going on!
