Spotted duckling

[Aussie dog]

One of my ducklings has these spots on her back. She's had these markings since I got her (she was one day old). She's a runner duck and I think she's blue or maybe chocolate. I've never seen a runner duck with markings like that.
Is this normal?

 

[Magnolia Ducks]

I have half runner blues and the spots and up being spots of darker grey feathers when the feather in. Nothing to worry about unless you value uniform colour.

 

[Aussie dog]

As long as it's just cosmetic I actually think it's kind of cool.
Thanks for your help!