One example from the first Mishna that appears on today’s daf is where animals that have been consecrated by two different people for the same korban are mixed up and we do not know which animal belongs to whom. In this case the Mishna rules that the kohen should sacrifice each animal for one of the owners. Rashi teaches that this means that the kohen should announce “this animal is being brought for its owner” without offering any specifics. Tosafot argue, however, that there is no need for that, since the priests are instructed to refrain from identifying the owner whenever sacrifices are brought, lest a mistake be made (see above, daf 2).
Some rishonim question whether this case may shed light on a question that is dealt with throughout the Talmud – yesh bereira or ein bereira. The question of bereira is whether when there is a question about the status of a given object, can an act that takes place later clarify the status retroactively. In this case, might we be able to conclude that yesh bereira – that the later sacrifice clarifies for us which animal belonged to whom in the beginning? Tosafot HaRi”d and Tosafot HaRosh both argue that this case is not a case of bereira at all, since we are certain that at the beginning one animal belonged to each of the two people who consecrated them; we do not have a case where it is unclear to us how to divide a mixture that is owned jointly by two people. Since each animal belongs to a specific individual, when the animal is brought without attribution, it simply reverts automatically to its original owner.