 What’s the same in sameness cases is a belief-state, not a proposition believed. When Gennaro and Hector both exclaim, “my pants are on fire”, and engage in similar associated behavior, it’s because they are both in the “my pants are on fire” belief-state. Being in that belief-state gets them belief-related to different propositions. It relates Gennaro to the proposition that Gennaro’s pants are on fire, while it relates Hector to the proposition that Hector’s pants are on fire. So the similarity is to be found at the level of belief-states, not at the level of propositions believed.