Luornu was the fourth hero to join the Legion of Super-Heroes, and she quickly developed a heavy crush on Superboy. After successfully completing many missions as Triplicate Girl, she suffered tragedy when Brainiac 5's robot Computo went rogue and killed one of her three bodies. To the surprise of the Legionnaires and in defiance of traditional Carggite physiology, Luornu's other two bodies managed to survived the loss of the third. She adopted the codename Duo Damsel, with the ability to split into two forms.