Complex sentence: In the case of past-life memories, the source of certain memories are attributed to the previous life; other people, movies, books, dreams, or an imaginary scenario then generate memories incorrectly attributed to having come from a previous life.
Split into simpler sentences: In the case of reincarnation memories, the source of certain memories are attributed to the previous life, but the source of certain memories could come from any number of places. Other people, movies, books, dreams, or an imaginary scenario could generate memories that are then incorrectly attributed to having come from a previous life.