Well, I am Visigothic. However, the question remains whether I can just give my kids double names and the regnal number will count just the first name.
To elaborate:
I am king Aurelio. I name my sons Aurelio Juan, Aurelio Pablo and Aurelio Ranimiro. Will they succeed me as Aurelio II Juan, Aurelio III Pablo and Aurelio IV Ranimiro or will they become Aurelio Juan I, Aurelio Pablo I and Aurelio Ranimiro I?
To my knowledge, it would most likely do the latter. You could always do a test game to confirm however.