Freda felt that I Vampiri did not succeed financially in Italy due to the country's audience reluctance to an Italian interpretation of the horror genre. For Freda's next film, Caltiki – The Immortal Monster, he used an English pseudonym of Robert Hampton to give the impression that the film was not Italian.
Freda felt that "I Vampiri" failed financially in Italy because audiences were not receptive to an Italian take on horror. To avoid this issue with his next film, Freda used the pseudonym Robert Hampton to make it appear as if "Caltki – The Immortal Monster" was made in England.