Not smelling it. They are definitely in the same chypre/leather category; I really like them both quite a bit, but I'm not smelling the similarities. Between Havana and Montana I do smell the similarities though.
You're no doubt smelling that which all chypre's have in common, the earthiness/mossiness in the base. Sometimes it's toned down, as in Pour Monsieur, but the tenor of it in Havana and Derby is comparable.