The subject of past life therapy is a vast and multi-dimensional field of practice, and depending on what view point you take, or your religious beliefs, there are several ways of working with this phenomenon.
The question of whether the lives viewed in a past life treatment were actually lived by you or not, is not central to my reasons for offering Past Life Regression therapy. This is a metaphysical question and best left to another time and place (no pun intended!)
What is central to my practice of Past Life Regression therapy is helping you resolve persistent and or recurring personal problems and recovering your sense of wholeness and personal power in the now. By finding and going into the first instance of a wounding or trauma, we can unlock the dynamic life force energy that has been held static in that time/space. Thus, activating and integrating the multi-dimensional aspects that exist within you.