Cayuga duckling with yellow stripes on head??

[DarlingMommy]

I'm thinking I got eggs that had been bamboozled by an outside duck.... They are from an Ebay seller who says they are pure Cayuga, but pics below. I'm thinking crossed with Rouen or Swede?? The yellow on his head is VERY clear and noticeable. :-( He's still adorable, but....

 

[Happy Quack]

Does not look like a Cayuga. The are solid black. It looks like a black Swedish or a mix.