When there's a mix-up of sacrifices and it's not clear who brought which offering, then the question of semihah - the laying on of hands on the animal - comes to the fore. Plus, what if the mix-up is between private ownership vs. public ownership? Or is the mix-up just the blood? And how - again - might it compare to the parah adumah? (Spoiler alert: It doesn't.) Also, all offerings can be intermingled and confused - a strong statement, when some offerings are always male or female, which should not be confusable, for example. Plus, a new mishnah - also about mix-ups, and where they should be treated according to the stringencies that are in each kind of offering (in the example, a guilt-offering and a peace-offering).