Everyone compares this to Vertigo but it reminded me a lot to Marnie
Blackstone was the evil side of Ruthland the guy who married Jacklyn and forced her to be with him while Chance is the one intrigued on her illness and is obsessed with helping her.
On a more subtle way Marnie also had a double personality coming from a horrible episode in her life.
Jackie came after the first abuse from Blackstone while Marnie started to steal since that episode when she was you g with her mom.
Maybe a troubled woman is a constant theme with Hitchcock and so is the obesssion with a blond woman, i need to see vertigo and maybe that ill find why the comparisons but i found a lot of similarities with Marnie.