A member of the Legion of Super-Heroes and a native of the planet Cargg, Triplicate Girl possesses, like all the inhabitants of her world, the ability to split into three separate, identical individuals and then merge again at will. Triplicate Girl's real name is Luornu Durgo.
In October 1962, when Superman is believed to be dying of an incurable malady, Triplicate Girl is among the Legionnaires who are summoned to the 20th century by Supergirl to help carry out the gigantic super-tasks that Superman hopes to fulfill as his final legacy to humanity, including the destruction of a "vast cloud of fungus in distant space that will some day reach Earth and blight all plant life," and the melting of the Antarctic ice, "to make Antarctica a fit place for millions to live in the future," thus ensuring "a home for Earth's expanding population...!" (S No. 156: "The Last Days of Superman!" pts.I-III). More recently, following the death of one of her three bodies at the hands of Computo (Adv No. 340, Jan 1966: "Computo the Conqueror!"), Triplicate Girl is re-named Duo Damsel.