I've had a revelation while watching "Blink"

Kathy Nightingale goes back to 1920 where she meets a man, marries him, and has three children, including a little girl named Sally, a beautiful little girl with dark hair, like her mother’s. 

Billy Shipton goes back to 1960 where he meets and marries a beautiful, dark haired girl named Sally.  

I’ll just leave you to ponder that for a moment.