If the blood of unblemished korbanot (offerings) were mixed together with the blood of blemished korbanot, you're not allowed to apply any of it to the Mizbeach (altar). The Torah prohibits blemished korbanot from being offered on the Mizbeach. So even though a person may only have the intention to offer the unblemished blood, bottom line, it is a disgrace for the Mizbeach for any blemished blood from a blemished animal to be offered on it. Therefore, it should be poured into the stream that is taken out of the Beit HaMikdash into the courtyard.
Now we'll talk about cases where we have cups of blood. The previous Mishnah was about the blood. Here, we'll talk about what happens if cups of blood—one from a blemished korban and one from an unblemished korban—became mixed up with each other. We're not allowed to apply any of the blood to the Mizbeach because, bottom line, one of the cups has blemished blood, and we don't know which is which. Therefore, we don't want to take the chance, and we do not offer any of them on the Mizbeach. But the Hachamim (the Sages) disagree. What do we do if a Kohen (priest) broke the law, took one of the cups anyway, and applied its blood to the Mizbeach? Kos be-kosot, if there was a case where a cup of blood from a blemished korban was mixed up with the cup of blood from a valid korban. Rabbi Eliezer omer (Rabbi Eliezer says). It says that if the Kohen, against the halakha (Jewish law), offered one of these cups, then whatever cups remained are also allowed to be offered on the Mizbeach. We assume that the problematic blood was already poured with that first cup, and the remaining blood is from valid korbanot. Therefore, you could proceed and continue to pour the rest of the cups.
And the Hachamim say that even if all of the cups were offered except for one of them—even if the blood of all the cups was offered besides the blood of one of them—we are not allowed to assume that the remaining blood is from one of the valid korbanot. Therefore, that blood is not allowed to be offered; rather, it should be poured into the pipe that takes it outside of the Beit HaMikdash.
This is the similar machloket (dispute) that we had earlier, where korbanot became mixed with a limb of blemished korbanot. How do we deal with it over there? It's the same machloket between the Hachamim and Rabbi Eliezer about what we do in that situation, and the machloket lines up just like it did over here. Rabbi Eliezer says that if one was already burned on the Mizbeach, the others are allowed to be burned as well, because he says that the invalid limb is nullified on a biblical level. And when we have one of them already burned, we can assume it's that. Well, the Hachamim disagree, and they say that even if all of the limbs besides one were burned on the Mizbeach, the remaining limb is not allowed to be offered.