duck marking question

[Quail27]

I bought a hatching egg lot off of ebay a while back. The eggs were supposed to hatch into blue crested runner ducks. I did not hatch a single blue crested runner duck, or even a single crested duckling (but that's another issue...).
I did hatch a duckling that looks like it is going to be solid white with one black (?) patch on the shoulder. I have never seen a duck that looks like this. Has anybody else? Is this a normal marking or do I have something special? If it is a common duck marking, is it something that a purebred Indian Runner duck should have?

I might be able to get a picture later, but I didn't want to go through the trouble if it's just the average duck.

 

[Quail27]

ADDED TO CLARIFY:

the duckling's patch is only on one shoulder, and it's on the side. It's not a patch that covers both shoulders or goes over the back.