Is That Me, You?
The idea of a doppelganger is an ancient concept that literature loves to this day. The term originated in German folklore. It meant a ghostly or paranormal phenomenon, usually as a harbinger of bad luck. Today it is more broadly defined to include a non-biologically related look-alike or double of a living person.
It is a concept fiction writers have loved since its earliest days. I am not much of a fiction reader (unless you count anything Trump says). But I do feast often on science fiction and here, too, the doppelganger often finds a home.