I know several people who are “Juniors” or “the third”, and they have II, or III on their driver’s licenses and social security cards.
That tells me their full, legal, registered name.
I even know one guy who has “Esq.” on his TDL. Weird, ain’t it?
In each case, I'll bet the the person with the Sr. or I suffix is still alive. Once he or she dies, the Jr. and II suffixes get removed, and III gets changed to II.
Nothing to see here people. Move along.