Emmanuel Bernard In the MappedSuperclass case I tracked this down into org.hibernate.cfg.InheritanceState; both "name" attributes end up in the org.hibernate.cfg.InheritanceState.ElementsToProcess#properties state. But honestly I have no idea where the proper responsibility lies for realizing that these are the same attribute: here, or in the code that uses this info.

In the extends-Entity case only one attribute ends up in the org.hibernate.cfg.InheritanceState.ElementsToProcess#properties state, so not sure where the duplicate column information comes into play yet.