Kes had no memories when she died.
as she was traveling back in time she didn't remember anything of her old life/lives, she just retained her new memories after each jaunt.
Are we sure that when they pulled her out of the biotemporal chamber in season three that she could remember the past at all?
As of the 21st episode of seaosn 3, with a exception of less than an hour flitting about in the future, little kes was a blank slate, with barely any loyalty to anyone on that ship.
She was faking it.