Major character who has only appeared on 1 page in the entire OOTS saga

[DapperWarlock]

So your claim is that Serini might have faked being two different people, while being invisible, after having already knocking out the two Paladins so they won't even know about it, and with there being no else around?

That feels less "improbable" and more just "nonsensical". And nothing about Serini's current mindset or her actions strikes me as nonsensical.

I'd actually find it pretty funny if Serini was just so isolated after three years holed up there that she turned one of her wands into a puppet and started talking to herself, like Donald Duck with that Mickey Mouse watermelon in the new Ducktales cartoon.