(f) the 2[ duty and interest, if any, paid on such duty] borne by any other such class of applicants as the Central Government may, by notification in the Official Gazette, specify; Provided further that no notification under clause (f) of the first proviso shall be issued unless in the opinion of the Central Government the incidence of 2[ duty and interest, if any, paid on such duty] has not been passed on by the persons concerned to any other person.