I think it is more likely that these are simply two similar characters.
Also, as far as contradictions go, the history/mythology of Nohadon and the KR is so old that it is very muddled. The actual history is likely different from any of the stories, much like the Arthurian myths.
Nohadon's ordinary man/ruler status is also similar to the Gilgamesh story in ancient mesopatamia where a common man with great *insert positive leadership quality here* becomes ruler through. The same line could be drawn between him and Arthur.