Terumos 7:5-6

Terumos 7:5

Let’s say that there were two baskets, one of terumah and one of chullin, and a seah of terumah fell into one of them but we don’t know which. In such a case, we assume it fell into the one that contains terumah (so non-kohanim may continue to eat from the basket that contains chullin). If we don’t know which basket contains terumah and which contains chullin and a non-kohein ate from one of them, he is exempt from repaying the extra fifth (because it might not have been terumah) and the other basket is treated as terumah. The basket that is treated as terumah is still obligated in the laws of challah (which doesn’t apply to terumah) because it might really be chullin. This is the opinion of Rabbi Meir; Rabbi Yosi says it is exempt from challah. If a second non-kohein ate from the other basket, he is also exempt from repaying the extra fifth (because what he ate might not be terumah). If one person ate from both baskets he repays the extra fifth (because he invariably ate terumah) but he pays it based on the smaller of the two quantities that he ate.

Terumos 7:6

If one of these two baskets (that we don’t know if it’s terumah or chullin) fell into chullin, it does not create meduma (because what fell might have been chullin); he treats the other basket as terumah and it is liable to challah, as in the previous mishna. This is the opinion of Rabbi Meir but Rabbi Yosi says it is exempt from challah. If the other basket fell into a different pile of chullin, it also does not create meduma (because it might be chullin). If both baskets fell into the same pile of chullin, it does create meduma (because there’s definitely terumah in there) but only based on the smaller of the two quantities that fell in.