I don't think they are nicknames, I think people just don't know how to spell his name..... :P

It has to do with the fighters origin, like try spelling any of these names BUT without looking at them: Serguei Lyakhovich, Krzysztof Wlodarczyk
Juergen Braehmer, Mariano Natalio Carrera....

Though in SalTheButchers case thats just the 'vodka' typing.....