i don't think they are snowy mallards becuase of the coloring.... Snowy mallards have deep pretty blue feathers on their wings.
The beak color looks like mini appleyards as well. The drakes tend to have a greenish bill and the female have orange and black bills. (from what i read, you can use their bills as an early indicator of sex when ducklings).
Mini apples also have racier looking bills/heads than calls, but not quite mallardy shapes. lol