So, there's a very niche topic that I was generating some fiction about using AI, and as part of that I gave one of the characters an unusual name. A few months later I again experimented with using AI for this fictional niche, and the AI just randomly chooses to use the same unusual name.
"Forebears" is a site that ranks the popularity of names. They rank the name I used at 324,668.
This is why I believe the AI can be significantly influenced by a single person.
What did you select for data controls?
Did you use the same AI provider both times? They might have just looked it up in the memory.