We dont have cascades here in Australia but from what I do know of them- They are supposed to be an auto sexing breed. Females with dark beaks- males beaks with lighter. But in your birds- the ones that look to have the light beaks look to have the female plumage colour, white the ones with darker beaks appear darker in the head and neck which is what one would expect in a male at that age.
Are they straight from a hatchery or a small flock breeder?
Only the females quack, so if you hear a quack coming out, it's a girl duck.
If you hear a raspy sound coming out, you have a boy duck.
If it has a curl at the end of it's "tail" you have a boy.
Here's a picture of a drake curl that I stole of the internet just for you.
Pretty Ducks. ~Finally someone with Golden Cascade Ducks...
I have a Male & Female. They are pretty ducks. They are very friendly. My male is bigger than my female, he's big/a good sized duck. But, he Only shows interest in the chickens.}}He Stalks them. lol The male GC has curl tail & makes a soft type noise. The female Quacks loud.~ "rainplace", described the ducks exactly like mine. I have GC eggs in the incubator, due March 8th (but, it's a Rouen drake that bred with her.) ~ How old are they? Julie