Sexing a mystery duck breed?

[itomura]

So, back in March I got two ducklings; a pekin and what I thought was a Cayuga. However, taking a closer look at the Cayuga, it seems she not only might be a he but also a Khaki Campbell. I am new to ducks, they are my first two, so you can imagine my inability to sex them. Any help would be greatly appreciated!
My Cayuga or Khaki, “Pickle”:

 

[nchls school]

A definite drake.

 

[itomura]

I suppose Pickle is a drake then...
So is he a Khaki? And Is it normal for khaki Campbell drakes to be quite vocal? My Pickle is always quack-chittering.

 

[Isaac 0]

drake

 

[nchls school]

He looks to be a Khaki Campbell, but I have never owned one so can not say on his vocalization.