A good illustration of multiple discovery (not strictly 'discovery' in this case, but anyway) too:

While Ettinger was the first, most articulate, and most scientifically credible person to argue the idea of cryonics,[citation needed] he was not the only one. In 1962, Evan Cooper had authored a manuscript entitled Immortality, Scientifically, Physically, Now under the pseudonym "N. Durhing".[8] Cooper's book contained the same argument as did Ettinger's, but it lacked both scientific and technical rigor and was not of publication quality.[citation needed]