Is there an advantage to submitting a QTAC and UAC application for the same program?
No. There is no advantage to duplicating preferences across UAC and QTAC. In fact, this may disadvantage you.
If you are made an offer in one TAC (Tertiary Admissions Centre) and fail to withdraw your application in the other you could at a later date receive a second offer from the other TAC. The second offer will over-ride the first even if it is for the same Griffith program.