Boston Brand was an elite acrobat for the Hill Circus, and a hero in his own right. Eventually, an assassin's bullet claimed his life during a performance as the sensation known as Deadman. Eventually, his twin Cleveland took over the costumed alter ego, and himself aided the innocent as had his brother. Both men met and worked alongside Earth-One's Batman on occasion.
Then there was James Brendan Corrigan, and his "clone" known as Spectre who assumed his identity for a time before the original James returned. An issue of the Amazing World of DC states that the Spectre was the Earth-Two counterpart of Deadman. While Spectre eventually journeyed to Earth-One to aid that world's Corrigan, his original "twin" remained on Earth-Two as would another version of Spectre in the Asgardian notional dimension which the Justice Society operated it for a timeless period.
While Spectre was a founding member of the Justice Society, Deadman assumed the alter ego for a time of Justice League founding member of Aquaman. Each hero worked alongside the first the especially during the Crisis on Infinite Earths.