Tashi delek! My question concerns the mantra reciting in Vajrayana tradition, where some Buddhist deities (not to be confused with the mundane ones) may have several versions of a same mantra.
That is, a mantra of a same deity may be either longer or shorter according to different sutras and dharanis.
In Vajrayana, it is also very important to receive a direct transmission of energy from guru (lama) before reciting any mantra.
My question is, can a Vajrayana practitioner recite another version of the same mantra if she or he has already (in a given reincarnation) received from her or his guru a transmission for receiting another version of the same mantra?
A reference to any root texts of any Vajrayana branch (Gelug, Sakya, Nyingma, Kagyu or Jonang) would be a great help.