Caio Domenico Gallo (1697-1780) was an Italian historian and literarian. Caio Mario Coluzzi Bartoccioni (1938-2012) was an Italian biologist and epidemiologist.
Also Italian.In Italian Caio and Gaio are both forms of Gaius despite in modern days it is decreasing in popularity. There is a way of saying where Caio is used as a name for a generic person along with Tizio and Sempronio. [noted -ed]
https://gl.wikipedia.org/wiki/Lista_de_nomes_masculinos_en_galego#N