An astounding number of the X-Men have been cloned, from Apocalypse to Fantomex. And throughout the mid-90s, one of the most prominent X-Men was Joseph, a clone who was essentially Magneto's good twin. But even though Joseph ultimately gave his life to stop one of Magneto's world-ending crusades, he's one of the few mutants who hasn't seemingly been resurrected on Krakoa so far.
Joseph's origins begin with an original member of Magneto's early Brotherhood of Mutants, Astra. She cloned Magneto after finding him in a coma following a battle with the Age of Apocalypse villain known as Holocaust. After a failed attempt on Magneto's life, Astra seemingly abandoned the clone, leaving him amnesiac when he first appeared in Scott Lobdell and Roger Cruz's X-Men #46 in 1995.
While recovering in a nearby orphanage, the clone took the name Joseph and slowly discovered that he had the power to influence magnetism. The orphanage was attacked by criminals, which forced him to use his powers and reveal himself as a mutant. Sister Maria, the administrator of the orphanage, advised he seek out the X-Men to build a life for himself.
The X-Men were understandably suspicious of the new mutant, who looked identical to one of their greatest enemies. After realizing the man had amnesia, they saw an opportunity to reform the individual they believed to be Magneto. After a battle with the Acolytes, a former team of Magneto's, Joseph also began to believe he was Magneto. This cemented his desire to be a better person, which endeared the X-Men -- especially Rogue -- to him.
The real Magneto would reveal himself in time, which put the idea that Joseph was the genuine article to rest. The villain had devised a plan to use the magnetism in Earth's atmosphere to grant himself incredible power in the "Magneto War" storyline. Alongside the X-Men and Astra, Joseph confronted the man he'd been created from. In order to stop the Master of Magnetism, Joseph sacrificed his life in a battle that ultimately left Magneto significantly depowered for some time after the fact.
Though he was indeed dead, he was resurrected by his creator, Astra, in Skottie Young and Clay Mann's Magneto: Not a Hero miniseries in 2012. This time, Joseph was a warped shadow of his former self. Abandoning the virtues he'd learned alongside the X-Men, Joseph now resembled the despotic Magneto of old. Astra also provided him with his own Brotherhood, made from deformed clones of classic members. He announced his return by slaughtering humans at an anti-mutant rally.
The Avengers questioned the real Magneto -- who was now spending his time with the X-Men -- and he had a solid alibi for his whereabouts during the slaughter. With the help of Emma Frost, the man who spearheaded the bloodbath was revealed to be Joseph. In order to subdue him, Magneto strong-armed Astra into betraying Joseph, and the duo were imprisoned on Utopia.
After escaping from Utopia, Joseph appeared once more to try and become a villainous Magneto. He rallied a new Brotherhood around him, though he didn't let them know his goal was to stoke fear, not protect mutants. This revelation saw the Brotherhood turn on him, most notably Juggernaut. Cyclops, the X-Men and Juggernaut defeated Joseph and displayed a want to reform him. Unfortunately, he was ruthlessly beheaded by Kwannon, who stated he was a threat to mutantkind in Matthew Rosenberg and Salvador Larroca's Uncanny X-Men #16.
This means that Joseph was not alive when the mutant nation of Krakoa was established, so he is not present on the island. Since Krakoa has a rule against creating clones, he's not likely to be resurrected either. While Krakoa is using genetic material and mutant powers to revive fallen mutants, it's not clear if Joseph is distinct enough from Magneto to even be counted.
However, Astra was granted refuge on Krakoa alongside several other X-Men antagonists. With his creator alive and well, there's always a chance that the rules could be bent in favor of his return. Still, it's hard to see Magneto being fine with another version of himself walking around Krakoa. For the moment, it seems like Joseph is one of the few mutants who won't be walking aroudn Krakoa any time soon.