Take the following case, Reuven kills Shimon and Levi בשוגג, he goes to גלות and the כהן גדול dies. Does Reuven go free or does he have to go back to גלות again to wait for the new כהן גדול to die as punishment/kappara for the second killing?
This would seem to be a machlokes Rashi and the Baalei Hatosafos on Chumash. Rashi quotes the Medrash that Hashem makes sure that everyone is punished for their actions. The Medrash gives the following example. Reuven killed בשוגג and Shimon killed במזיד both without witnesses. Hashem will then arrange it so that Reuven kills Shimon in front of witnesses so that both get thier punishments. Reuven will go to גלות and Shimon will be killed. The Baalei Hatosafos ask on Rashi, Reuven is chayav to go to גלות twice once for the first killing with no witnesses and once for Shimon so how is he getting his punishment? We see clearly that they hold that each killing needs a separate גלות. Rashi on the other hand would seem to hold that one period of גלות can serve as the pubishment for a number of killings and therefore Reuven's one trip to גלות serves as teh complete punishment for both the killings.