Two fathers and 2 sons each shot a duck and none of them shot the same duck Only three ducks were shot How could this happen?

There are 3 people. 2 of them are fathers and 2 of them are sons. explanation: My Grandpa, Dad, Brother shot 3 ducks. Each got 1 duck each, because my Dad is a father and a son. Fathers: Grandpa, Dad Sons: Dad, Brother. Quack!