I think part of the problem ist that derivation hashs sometimes don't fully cover the intermediate states of a derivation during the build process. This might l

I think part of the problem ist that derivation hashs sometimes don't fully cover the intermediate states of a derivation during the build process. This might lead to two hashs pointing to effectively two different configurations. I've had that experience in particular with non-reproducible derivations. Even one of those in the store will make the store, or at least a subset of it, a state.