Yoma 64B

ואם היה השני מובחר ממנו ⁠— יביאנו.

And if the second one was superior to it, he brings that one. This demonstrates that according to R' Yosei, when the two animals become fit for sacrifice at the same time, preference should be given to the first one unless the second one is superior.

אמר רבא: דיקא מתניתין כוותיה דרב, וברייתא כוותיה דרבי יוחנן. מתניתין כוותיה דרב, דקתני: אם של שם מת ⁠— זה שעלה עליו הגורל לשם יתקיים תחתיו, ואידך כדקאי קאי.

Rava said: The language of the Mishnah is precise in accordance with the opinion of Rav, and the language of the baraita is precise in accordance with the opinion of R' Yoḥanan. The Talmud explains: The language of the Mishnah is precise in accordance with the opinion of Rav, as it teaches: If the one to be sacrificed to God died, that goat upon which the lot for God was drawn should stand in its stead. And the other goat stands as it stood before, i.e., its status does not change, in accordance with the opinion of Rav.

ברייתא כוותיה דרבי יוחנן, דקתני: ״שני״, איני יודע אם שני שבזוג ראשון אם שני שבזוג שני, כשהוא אומר ״יעמד חי״, ולא שחבירו מת. מאי משמע? ״יעמד חי״, ולא שכבר עמד.

The language of the baraita is precise in accordance with the opinion of R' Yoḥanan, as it teaches: When the Mishnah says that the second goat is left to graze, I do not know whether it is referring to the second goat of the first pair, or the second goat of the second pair. When the verse states: “It should be stood alive before YHWH, to make atonement over him, to send him away to Azazel into the wilderness” (Leviticus 16:10), it is not referring to the goat whose counterpart died. The Talmud asks: From where may it be inferred, i.e., how does the verse indicate this point? The Talmud answers that it states: “It should be stood alive,” in the future tense, indicating that it is not referring to the one that already stood with its counterpart that died.