Yeah im pretty sure he did. I think it was the one when he heard Damian call her Lucia and he kinda got jealous(but im not sure coz its been a long time since i last read the novel)
i think he quastioned her because he didn't know her childhood/real name was Lucia but she told him to call her Vivian. She started to like that name because he always calls her so. She accepted that she is both Vivian and Lucia.
and i think he is the only one calling her Vivian. other call her Duchess or whatever they do...
so basically Lucia for friends and Damian and Vivian for lover
Someone knows, if Hue will calling the MC, Lucia someday (=・ω・=)