I frown at him, they both have the same Patronus. It is not a rare Patronus, but just like being an Animagus the Patronus is based on your personality. That is why a lot of people have the same Animagus form as their Patronus, but some can differ, it is rare, but some people are really complex. Not a lot of people become Animagi, it is difficult to find the right information and have the right dedication.