Anyone know what breed of duck this is?

[Poultry parent]

Ok so I have four 8 week old ducklings, 2 Pekin, 1 that I think is a mallard, and 1 that kinda looks like a mallard but it has a thick neck ring, does anybody know what king of duck he could be? (And no I'm not sure that he is a he)

 

[bell1774]

To tell the gender you just see if it's voice sounds kind of like Donald Duck or like rigid and cracky that means it's a boy. It does look like my little mallard even with the ring. It could be a mix of a mallard and another duck. Your ducks are very pretty

 

[Poultry parent]

Thanks! I think they are pretty too.
I know you can tell them apart by voice, it's just my first time owning ducks so I don't know what the sound difference is, I think I'm going to wait till they lay to see who is a drake and who is a duck, then I will compare voices so I know for next time