they explained it, they built up a partnership with LDNU, but I think its like a pre-order of their roster
Once this season gets done they will drop their french roster
The mostly Lithuanian (OG LDN UTD) roster is playing in a different league (EMEA VCT) than the French OG (the French Regional League), so that alone doesn't seem to be enough of an issue that would require Riot stepping in and issuing rulings.