Unsettling Twins is a common Creature — Human card from Duskmourn: House of Horror (DSK), collector number 38. Current market price: $0.12 (foil $0.17), TCGplayer market prices via Scryfall.
When this creature enters, manifest dread. (Look at the top two cards of your library. Put one onto the battlefield face down as a 2/2 creature and the other into your graveyard. Turn it face up any time for its mana cost if it's a creature card.)