a dead ringer for someone

INFORMAL

COMMON If you say that one person is a dead ringer for another, you mean that the first person looks or sounds exactly like the second. He's tall, dark and a dead-ringer for Robert Pattinson. Kovic is extraordinary in one respect: he's a dead ringer for the former US President. Note: The word `ringer' may originally have come from a name for dishonest traders at fairs who sold brass rings, pretending they were gold. In American horse racing, a `ringer' is a horse that has been dishonestly substituted for another in a race.