The history of science and technology is riddled with claims and counterclaims regarding discoveries and inventions. Today's Wall Street Journal features this front page article: Alfred Russel Wallace's Fans Gear Up for a Darwinian Struggle. The claim is that Darwin stole many key ideas about evolution from Wallace.
History usually does a good job sorting out priority. The biggest problem is that people confuse thinking of an invention (or theory) and making it happen. Sure, Darwin borrowed ideas from others, but he put them together in a more convincing package. And Alexander Graham Bell fought off no fewer than 600 challenges to his patents as he and his partners transformed his simple device into a thriving business.
Inevitably, some people's thinking evolves from "Why didn't I think of that?" to "I did think of that." As I describe in my book, The History of Wireless: How Creative Minds Produced Technology for the Masses, Charles T. Jackson claimed he and not Samuel F.B. Morse invented the telegraph. Jackson also claimed it was he and not William T.G. Morton who was first to conceive the use of anesthesia in surgery. Another prolific retroactive inventor was Daniel Drawbaugh; he waited until 1880 to announce that he invented the telephone years earlier. He resurfaced in 1903 claiming he, not Marconi, invented radio.