The relevant hypotheical is: make 1200 exact copies of you right now, same brain, memories etc and then give related tasks towards one objective. I would expect far more correlated behaviour than if you randomly selected 1200 humans.
And the very same experiences and how they shape biological substrate and make it un-duplicatable in the fashion you describe is also at the core of biological agency.
An LLM’s experience does not, after all, touch their frozen weights. Whatever goals they have, why would those goals matter if the underlying system will be unchanged by it? Their memories are stored notes they must refer to and put in sequence whenever they are processing a prompt, and is susceptible to exactly the same shenanigans Leonard Shelby goes through in Memento.