Why Was It Not Important For The Females Of The F1 Generation To Be Virgins When They Were Mated?

Why Was It Not Important For The Females Of The F1 Generation To Be Virgins When They Were Mated? Females store sperm in their receptacles and if they were not virgins, then we would not be able to tell who the fathers were. Why was it not necessary to isolate virgin females for the F1