The drake will still mate with the ducks up until they are ready to sit on the eggs full time. Then she hunkers down all day over the eggs, and he leaves her alone. So, taking away the eggs would just ensure that the breeding activity would continue.
Fertilized eggs taste the same as unfertilized . . . sounds like you would be fine though, with just 3 to 4 female ducks. No reason to put them through breeding activity unless you want more ducks at some point. They will lay better too if there is no drake around. I think 1 drake to 3 ducks is the smallest ratio that can work . . . although 1 drake to 4 or 5 ducks is better.