Doppelgänger: A ghostly counterpart of a living person, or a sinister form of bilocation. Today the term is often used to refer to a lookalike.
German from Doppel (double) and Gänger (goer).
"My friend is a huge fan of Erwin Schrodinger so I can't say I was surprised when he adopted two twin kittens, naming one 'Cat' and its doppelganger 'Same Cat."
