MALE MALLARD IN ECLIPSE PLUMAGE (NONBREEDING) & FEMALE MALLARD, ASHBRIDGE'S BAY PARK, TORONTO, ONTARIO, 8/3/2023

   I believe the Mallard in the foreground is a female and that the Mallard in back of it, is a male in eclipse (nonbreeding) plumage.   This is because the Mallard in the back has an olive-yellow bill with no markings on it.