Duplicate inventions happen all the time: Mendeleev (Mendeleyev) spent part of his life re-discovering and re-inventing stuff... because most of the inventions

Duplicate inventions happen all the time: Mendeleev (Mendeleyev) spent part of his life re-discovering and re-inventing stuff... because most of the inventions and discoveries took time to spread to his native Russia. And Mendeleev's own Periodic Table was re-discovered :) by Lothar Meyer http://en.wikipedia.org/wiki/History_of_the_periodic_table http://en.wikipedia.org/wiki/History_of_the_periodic_table