Zevachim 74A

ותנן, רבי אליעזר אומר: אם קרב הראש של אחד מהן ⁠– יקרבו כל הראשים!

And we learned in a Mishnah (77b) that in a case where sacrificial portions from unblemished burnt offerings became mixed with sacrificial portions from blemished burnt offerings, which are disqualified, R' Eliezer says: If the head of one of them was sacrificed on the altar before they knew of the blemish, all the heads should be sacrificed, as it is assumed that the head of the disqualified animal was the one already sacrificed on the altar. This indicates that even with regard to slaughtered animals, if they were rejected from the altar due to being in a mixture, they are not permanently rejected, but are fit after the fact.

הוא דאמר ⁠– כחנן המצרי; דתניא, חנן המצרי אומר: אפילו דם בכוס ⁠– מביא חבירו ומזווג לו.

The Talmud explains that this Mishnah affords no proof, as R' Eliezer states his ruling in accordance with the opinion of Ḥanan the Egyptian, who maintains that even slaughtered animals are not permanently rejected. As it is taught in a baraita that Ḥanan the Egyptian says, with regard to the two goats of Yom Kippur, the one sacrificed to God and the scapegoat designated to be sent to Azazel: Even if the blood of the sacrificed goat is already in the cup where it was collected and the scapegoat dies, the sacrificed goat is still a fit offering, and the priest brings another goat and joins it to this slaughtered goat to serve as the scapegoat. By contrast, the other tanna’im, who maintain that slaughtered animals are rejected, hold that once they have become rejected due to being in a mixture they are no longer fit for sacrifice, as stated by Rava.