Nope. I can tell mine apart with ease! There's plenty of differences among WHs, for example, my two have different amounts of white and brown; Puddles has a tan/white feathers on the front, but Quackers is mostly white there. There's other differences, too, that's just an example. It's probably harder to tell ducks with solid colors apart, like KCs, since there's no patterns, really.
I have a question: My 5 week old WHs have grayish yellow bills, so what does that mean? I've heard that it may mean they're boys, but one was sexed as a girl, and they both had the black stripe/spot on their bills when they were younger. They are from Metzer, which doesn't breed for show, so does that mean I may just have girls with yellow bills? If so, is that a "defect"? Thanks