There were forged Semeuse stamps of the early 1960's also with forged cancels.
They are in fact rare.They were made in Korea for political reasons.In this link explications:
http://www.timbresmag.com/2016/04/2...es-en-coree/As far as the early Semeuse stamps go;there were many types of forgeries but
mainly to defraud the post;and most of these had authentic cancels on them.