Both "A Princess of Mars (1912)" and "At the Earth's Core (1914)" are written by Edgar Rice Burroughs. Different setting, same style, same story, with a couple of tweaks. Man goes on a journey to another land, falls in love with a pretty girl, offends her by not knowing the customs, some adventure, go to rescue the girl, He being faster, smarter and braver, no major problems.
The critical reception on Wikipedia makes no mention of the similarities. Was there published criticism mentioning essentially identical plot, in the early 1900s?
