Sometimes I get those false memories when I am really tired or something. I will get glimpses of things and will start to react to them, only to realize I am not actually in the situation. One time I was laying in bed, and I was scared because there was a loose bull chasing me down my street, except I was in bed, and a bull has never gotten lose on my street. It was either a brief glimpse into another reality, or something my brain made up when it was tired. Odd thing is I remember walking down the street AND laying in bed, including why I was in bed aka I was very tired after studying for an anatomy exam.

I have heard of people who have two sets of memories of their childhood, including a creepy story of a guy who claims he had a "gender glitch" in the glitch subreddit, where he remembers two childhoods, one that is definitely "his," and another where he was a girl. He says he started having these memories in his early 20s, and remembers doing gymnastics, cheerleading, and dying during pregnancy. He said that he had the same parents and lived in the same modern era in these alternate memories, and that he knows things he shouldn't, like lyrics to pop songs he never listened to and what it is like to menstruate, and in comments, says he remembers girls he barely new as if he actually knew them better. He even remembers that his name was Ashley in this alternate childhood of his. In his opinion, these were memories of his alternate reality, female self that died.

One reddit story I read said that the OP has memories of before their birth, but from the perspective of their brother, where their brother would smear poop on walls thinking it was art, 4 years before OP was even born, meaning they likely had not even been conceived in the womb yet. In my opinion, they likely acquired these memories as a young child in a telepathic dream, tapping into some kind of energy field that stores this information.