How do i tell if their mixed with mallard

[just duckee]

I've been buying muscovy ducklings to pick colors for next year's breeding program.
I bought these 15
I always wonder in the back of my mind, what if they are mules, how would I know?
These look like my other muscovy except I thought they where fluffier when I first got them.
The ones color is strange to me.
Any ideas on how a person would know?
I'd like to keep the 4 different wild colored ones and 2 blacks. But not if their mixed with mallard.
FYI. The lady I bought from said they where not mixed, but still question as This was a meet up buy and I don't know the farm.
Thanks if any one can help!

 

[Northwest_Wannabe]

When they mature it may be easier to tell, did the person you bought them from own any other species of duck?

 

[just duckee]

That's the problem, I know nothing definite about what was at the farm.
Thanks for your reply. Do you know what i'd be looking to see if they we're mixed

 

[chickens really]

In your pictures I don't see anything indicating they are crosses. They look like Muscovy Ducklings.

 

[just duckee]

Thank you for your reply.
I'll relax and wait until they feather up and God willing they'll be beautiful muscovy.