Confusing duck gender

[Duckmobile]

I have 2 runner ducks thought to be a male and a female, I have been getting 2 eggs a day 4 the past few days. Yesterday I saw the female on top of the male, mating. Now I don't know which one is the female that has been laying eggs. They will not be separated and the female has always been the larger one.

 

[Moochie]

Any curls on the tails?

 

[Duckmobile]

The male one had a drake feather but it fell off