My husband occasionally incorporates things that happened to others into his memories as if they happened to him. I recall telling him about something a coworker told me, and a year or so later, it became something that happened to him. It wasn’t anything significant - just the sort of thing one talks about when making small talk - but I found it weird that he co-opted the story. And I think he truly believes it happened to him.
I don’t bother correcting him unless it’s something that matters - like dates in his medical history. He thought his first spinal surgery happened 8 years before it actually did. Since he was talking to another surgeon, it mattered that the dates were correct.