Gary Hieftje and the phenomenon of coincident discovery

Inventions appear not to come out of the blue but rather to spring to life when the time is ripe. s certainly true for analytical atomic spectroscopy, where the three main inventions are generally associated with one prominent name, whereas in fact all three were proposed by two independent researchers. Drawing from our own experience we shall demonstrate that shared ownership can also be observed in more mundane examples. Is this a simple case of concurrent development or is there also a competitive element?