Can a manager of a little league team umpire a game in the same league?

I was at my nephews little league game. My brother is the manager of their team (Diamondbacks). They were playing the Cardinals. They were undefeated as are the White Sox. Well, the White Sox manager umpired behind the plate in that game. Not saying he did a bad job just asking if a manager of a little league team can umpire a game in the same league?