Hullin 30: The Many Paths to Shechitah

If there's more than one incision in the pipe, can that be kosher shechitah? It's a machloket. What about 2 people holding the knife for one animal's slaughter? That's one incision, but 2 people with 2 knives, which means 2 incisions, and it has all kinds of insecurities associated with it - and could result in non-kosher shechitah, but we really don't worry about that, and allow it. Note the many cases of shechitah that are left without conclusions. Also, a new mishnah: 1 person who slaughters 2 animals simultaneously; likewise, the 2 people holding one knife (as presented in the Gemara on the daf right before the mishnah), even with 2 cuts -- all of those cases are kosher shechitah. But decapitation in one motion is not considered valid. With the possibility of it being kosher if the length of the knife is the breadth of the animal's neck.