As of 1/29/15 , on the website for his book The Improbability Principle, statistician David Hand starts with the story of the simultaneous publication in the US and England of the cartoon character Dennis the Menace in March, 1951.
Cartoonists in both countries introduced audiences to a trouble-causing little boy named Dennis, each of whom had a dog who helped create the chaos. The boys were quite different in their attitudes but not their results. The British Dennis intentionally caused trouble, while the American Dennis, always good-natured and angelic, consistently stumbled into trouble. Both boys were immensely popular. They each had hit a cultural pleasure nerve—the archetypal bad boy.
The British Dennis had gone to press ten days before the publication of the American Dennis, so there was no evidence of plagiarism
Professor Hand suggests that this coincidence is an example of low probability events that happen in large populations, sometimes known as the law of very large numbers. He does not recognize the phenomenon of simultaneous discovery, a well-established subset of coincidences. Simultaneous discovery appears to have an explanation more complicated and more specific than the law of very large numbers. The low probability draws our attention but does not explain the coincidence. It appears that cultures evolve with explorers on the edge, those seeking ideas that fit with current cultural interests, needs, and demands. The telephone, for example, was invented by two Americans each of whom presented their discovery to the US patent office on the same day: February 14, 1876. Also on the same day, Google and Stanford University separately announced the enhanced capacity for computers to recognize images. Each did not know the other was working on the project. There are hundreds more examples most without evidence of plagiarism.
The simultaneous appearances of two Dennis the Menace and many other examples suggest that it is probability at play but another form of explanation involving cultural curiosity and need. “When the time is ripe for certain things,” remarked the Hungarian mathematician Farkas Bolyei, “they appear at different places in the manner of violets coming to light in early spring.”