Getting two eggs a day is not unheard of but it is a bit unusual to get them consistently. It takes 25 hours for an egg to go through the process of being made by a chicken so I assume it's about the same for a duck. I have an all hen flock and my ducks mount each other sometimes, especially in the big kiddie pool. If they are both quacking you have two hens. Also a drake would have a tail curl is the breed comes from Mallards.