Duplicate Boy was created by science fiction writer Edmond Hamilton, who created the backstory for the character after it was submitted by a fan named Thea Temple, and was credited for this by DC Comics.
Duplicate Boy was a member of the Heroes of Lallor, he was one of the five born and was raised alongside the other heroes by the government, only to be banished for disobeying the dictatorship of the planet. Later Duplicate Boy as well as his four teammates are tricked into battling the Legion of Super heroes by a relative of the Jungle King. However, Duplicate boy and Shrinking Violet fall in love despite their teams hostilities.The two teams eventually part peacefully remaining as allies.
Duplicate Boy along with the rest of his team then assist the Legion as well as the entire universe in battling Darkseid as well as his Daxamite army, in their attempt to conquer the universe.Following Darksied's defeat, he and along with the rest of the Heroes help in rebuilding, but during this he uses Superboy's telescopic vision to spy on Shrinking Violet, who he learned had started a relationship with fellow Legionnaire Colossal Boy,earning him Duplicate Boy's wraith.
Duplicate Boy later tracks down Colossal Boy, and gives him a severe beating for his relationship with Violet. Only to stop when he notices that she isn't the true Shrinking Violet, so he leaves without telling anyone what he has learned. Eventually Violet returns, following having been kidnapped by rebels of her home planet Imsk, and replaced by the Durlan, Yera Allon. Once Shrinking Violet learns that Duplicate Boy had learned of her being replaced, and kept it a secret she ends their relationship.
Duplicate Boy is possibly the most powerful being in the entire 30th century thanks to his ability to copy any super power he has ever seen. He frequently copies many of the powers of Superboy as well as various other members of the Legion. Unlike most power mimics, he can mix and match superpowers from several superbeings at once, and he does not mimic their appearances or their weaknesses when he mimics their powers except when absolutely necessary (so he never gains Superboy's vulnerability to Kryptonite). It is unknown how long he can sustain a given mimicry.
Marital Status: single
Known Relatives: none
Group affiliation: Heroes of Lallor
Base Of Operations: 30th century
Height: 6‘2” Weight: 200 lbs Age: In his twenties
Eyes: Blue Hair: brown
Duplicate Boy is a big, fit, and very muscular athletic man with brown wavy hair, and has blue eyes. He wears a green costume that leaves his face and hands bare. His boots, wrists, torso, and trunk are black with white colored diamond designs.