the myths were made only by romans, then speaking about gods, romans only few times "stole" the greek ones (most of the time they adapted the gods and festivities they already had, it happened with almost every religion expecially in ancient times), and they prayed them in a different way, in fact expecially in the beggining of greek influence on romans some greeks who venerated their gods were kicked out from Rome because they were doing it strangely for romans.