from wikipedia: Cryptomnesia occurs when a forgotten memory returns without it being recognized as such by the subject, who believes it is something new and…
Absolutely. There’s lots of reasons that this phenomenon could occur. Fictionflickers come to mind too as a possible source for xenomnesia.
As far as I’m aware, there’s not a word for this, but I think one would be really useful Amnesia- meaning not remembering- is from…