Not quite the same as the prompt but it works.

Courage has amnesia so she doesn't remember her past when she still lived on the surface. For better or worse, she wouldn't even recognize her past self as her. She'd see her as a traumatized child who she'd try to help, not even knowing it was herself. [Also, as much as I would've wanted Courage to comfort her past self in some way with physical contact, I don't think she'd like hugs or even just a hand on her shoulder. She'd probably freak out and accidentally summon a magic attack].

Not sure if she hit her head when she fell or something else happened. She was also able to reset in her AU but she also doesn't remember those either, most likely due to The Fallen [whoever is Chara's role] in her world. Courage has been through a lot and yet she still acts positive despite everything...

*It's still her.