It depend on where they live, In Nigeria its just polygamy, I don't think its illegal there and if it is, its not enforced. here in Canada the guy is definitely looking at jail term if he legally marry the two of them, but if only one is done legally the one with the legal marriage is the wife and the new wife better hope he's legally married to his first wife so she can get a quick annulment and save her business or just be the concubine. there is no law against that either