Definitely two meanings, and they really depend on the attitudes of the user, and what the user thinks is fake or real. So:
A) "Pretentious" can be a useful phrase to describe something that is fake or pretend, or somebody who is pretending in order to conform. Sometimes it is still used that way.
B) Its meaning has also become completely the opposite. In the English-speaking world, "pretentious" has become a catch-all phrase to criticize anything or anyone that is vaguely heartfelt, intellectual, earnest, sincere, artistic, unconventional, nonconformist, non-commercial, or not on TV, on Youtube or in the supermarket.
Take your pick:
A) The blonde in American Beauty, Angela Hayes, lied about having lost her virginity and being sex-mad. In fact, she was an insecure virgin, and worried about what people would think of her. So she pretended to be a slut. She was pretentious.
B) The lonely boy in American Beauty, Ricky Fitts, who thought the plastic bag in the wind was beautiful couldn't really have thought that, he just wanted to be different from other people, and was pretending to be deep. He was pretentious.