I concur, if you are getting two eggs a day, and only have two ducks, they are both female. They are playing silly hop on pop games.
My ducks are mostly lesbian I think. they run from the boys more than other girls. I have seen them make duck sandwiches 3 and 4 ducks deep while in the pond. That poor bottom girl nearly gets drown. LOL Duck mating is brutal. It is mostly dominance games with the girls.
I understand your confusion though, In my mixed flock I have one pekin that hardly says anything at all. She is very quiet. and when she does speak up it is soft. Not quite like a drake, but not like a duck either. She never got a drake feather. and she recently started laying eggs. Up till the eggs came I was not convinced one way or the other of her sex.
