Familiar names from the history of the Israelites can sometimes take on different meanings depending on the context. When historical records list leaders and participants, it is easy to assume that well-known names refer to broad ancestral groups. A reader might naturally think that references to Judah and Benjamin indicate the involvement of those entire tribes.
However, in this specific account, these names do not represent the broader tribes of Israel. Rather, they belong to two distinct individuals. They are simply the personal names of two officials who held positions of authority.