Mishnayos Kerisos Perek 5 Mishnah 4

The mishna resumes discussion of the provisional guilt offering. If one had a piece of non-sacred meat and a piece of sacrificial meat, and he ate one of them and does not know which of them he ate, he is exempt from the obligation to bring a guilt offering for misuse of consecrated property. Rabbi Akiva deems him liable to bring a provisional guilt offering, in accordance with his opinion in the previous mishna that one brings a provisional guilt offering even in a case of uncertainty with regard to misuse. If he then ate the second piece, he brings a definite guilt offering, as it is certain that he ate the sacrificial meat. If one person ate the first piece and another person came and ate the second piece, this first person brings a provisional guilt offering and that second person brings a provisional guilt offering; this is the statement of Rabbi Akiva. Rabbi Shimon says: Both of them bring one definite guilt offering as partners, and they stipulate that the one who ate the non-sacred meat grants his share of the animal to the one who ate the sacrificial meat, and the guilt offering is sacrificed on his behalf. Rabbi Yosei says: Two people do not bring one guilt offering, as one may not sacrifice atonement offerings conditionally.