There were arguments between Beis Hillel and Beis Shammai in Halachas that were Chayav Korban/Kares.
What happened if a person was a follower of Beis Shammai and sinned unknowingly? According to him, he'd have to bring a Chatas.
He comes to the Beis Hamikdash, and lo and behold, all the Kohanim happened to be Beis Hillel followers. According to them, this sacrifice that he's bringing isn't a sacrifice but Chulin Shenishchetu Be'Azara!!
So they, Leshitaseichem, can't eat it or Shecht it (they can't even say "Safek Olah").
Do the Kohanim have to bring the sacrifice nonetheless?