Not knowing, I got a reply from a respected birder friend.
She says the Central American (true) Muscovie duck will hybridize with wild ducks, including the pintail -- your likely foreground two ducks/mix. The muscovie itself looks similar to the one furthest away in your picture -- only bigger. (May be the "rooster duck", too).
They're mutts, all right. (Nothing against mutts, you understand).
