The Schizoid Man

S1, E5: Number Six awakes one morning in a different Village and discovers things have changed. He has a new appearance, has become left-handed and has a different taste in foods. He is no longer Number Six but now Number Twelve. A doppelganger of Number Six has been brought to The Village in an attempt to crack him. A bruised fingernail is the only clue that can help the real Number Six.