Lady Stefanie and her friend wanted to cane the shit out of this guy because he had been misleading them. Instead of doing the things they asked him to help them with, he was busy misleading them hoping to cash in on that. But they realized before long and corrected course. But he had to be punished and they did it by caning his bare butt as painfully as possible.
Goddess Lena was out to get her way and she did not hesitate to do so. The mistress had to make sure that this slave learned his lesson the hard way and that he stopped being a joker. The mistress was punishing him because he had failed to do things her way and so she caned him so that he became more serious. He learned his lesson the hard way.