My opinions is that It looks like a little Mule Duckling (Muscovy Mix... probably with Mallard). It's very cute. I have hatched a couple that look a lot like it, but they were Muscovy/Pekin mules. 27 days is about right for mules.
But I could be wrong though but if those are the only 2 breeds they have it's not impossible that it happened.
But I could be wrong though but if those are the only 2 breeds they have it's not impossible that it happened.