J'onn J'onzz and Roh Kar were both products of the 1950's. In 1953, Roh Kar teamed up with Batman and Robin of Earth-Two (in Batman #78). J'Onn J'onzz first appeared in an adventure on Earth-One (in Detective Comics #225). According to the Batman Encyclopedia: "Roh Kar arrived on Earth-Two and was aided by Batman in apprehending the renegade Sax Gola". Earth-Two's Batman had previously visited Mars but never had occasion to meet this Manhunter from Mars. On Earth-One, J'Onn was accidentally pulled from his native world by a teleportation device created by Professor Erdel Possessing superhuman powers on Earth-One, J'Onn posed as the Martian Manhunter. Roh had to rely on a jet pack and technology to give him the edge in battles with the criminal element. Both of these became known as the Manhunters of Mars 1 and 2
On Earth-One, a Latin American president named Pedro Gomez was given one of two rubies that gave him power of insight with which to lead and protect his people. Bequeathed to him from when he was young, his life paralleled that on stage performer John Sargent of Earth-Two, although John took on the alter ego of Sargon using his ruby to control all that he touched. John became a member of the All-Star Squadron and an ally of the Justice Society of America, and this John like John a Jones had lengthy careers as caped crusaders masquerading in suit and tie.Roh Kar and Pedro Gomez only appeared once each, their counterparts the two John's were stalwart superheroes for a decade before leaving their respective Earths. Eventually, J'onn left Earth-One to assist his people in finding a new home after Mars-One became inhabitable. John eventually left Earth-Two, migrating to Earth-One for unspecified reasons to have a few non-chronicled adventures before becoming an adversary of the Flash and Wonder Woman while under the influence of a criminal mastermind, although Sargon he aided the Justice League against a galactic threat and became an honorary member before retiring for a time.
Additionally, both Johns had ties to two green ancient artifacts named after their creators Diabolu and Asyreth. On each world, there was a second set of rubies fashioned into rings, on Earth-One is was used by an actor who was an agent aiding the Justice Lesgue, and on Earth-Two it was usd by a criminal to oppose the Justice Socialite Spectre. Eventually, both John Jones and John Sargent would return to their native Earths just prior to the climax of the Crisis on Infinite Earths.