Temurah 5:1

One may act disingenuously regarding a firstborn animal as follows: if an animal is pregnant for the first time, the owner can say that if the offspring is a male, it’s a burnt offering and if it’s a female, it’s a peace offering. Then, if it’s born male, he brings it as a burnt offering and if it’s born female, he brings it as a peace offering. If he said to let a male be a burnt offering and a female a peace offering and the animal gave birth to both a male and a female, each is offered accordingly. (This is disingenuous in that it keeps a firstborn male from being designated for a kohein.)

Temurah 5:2

If the animal gave birth to two males, one is brought as a burnt offering and the other is sold to another person who needs to bring a burnt offering; the money from this exchange is not sanctified. If the animal gave birth to two females, one is brought as a peace offering and the other is sold to another person who needs to bring a peace offering; the money from this exchange is not sanctified. If the animal’s offspring is a hermaphrodite or of indeterminate gender, Rabbi Shimon ben Gamliel says that it acquires no sanctity.