I tried to keep two drakes with six hens with bad results. Maybe ten will be better. But, my issue was that they would purposely chase and rape the other drake’s girls. I think it was more about dominance than anything else. If I were in your situation and I had a good home for those drakes, and I would only keep the one. However, if I was planning on getting more ducks in the spring, I would rehome all the drakes and keep one (or maybe two) from the batch in the spring. That way you don’t have to worry about an older drake getting with a too young hen. It also merges your flocks sooner rather than later. Just my opinion.I’m thinking about keeping one or two of the drakes. If I keep two then I plan on getting at least 3 more females to have 10 females. I will still have to keep him separated from 5 of the females until they are another month or so older but I guess I could put the two females and him together. Those 3 are the ones I’ve had since may.