You can keep ducks in pairs, 1 drake and 1 hen will do fine. So if you get rid of one drake you could keep a pair. A single drake will rarely over breed hens. For the past 2 years I had just 1 pair of Muscovy ducks and the drake would never over breed. For the past year I had 1 Pekin drake, 2 Rouen drakes and 2 Rouen hens and they did not over breed at all either. Right now I still have the 3 drakes and 2 hens and they have still not been over breed, but for Muscovies I have 2 drakes and 5 hens, none of them over breed either.