I have Murray Mcmurray Rouens and Khakis, one pair each and they hatched out a crested In August. I do not know which combo of breed(s) the duckling is. Could be any combo of those 4. The Rouen was the broody who hatched it.
These pictures are of the hatchling after her feathers came in after a few months.
These are of the duckling just days after hatch.
I forgot to add that we incubated and hatched between 15-20 eggs from these same ducks and none of those were crested.
Love that baby she turned into a beautiful duck.