Why is it Always Leo?

I have my history midterm this afternoon, and I'm tryiing to study. It's a lot of remembering names, and events that all have really silly names. My main worry is that I will spell them wrong. I generally know what happens, it's just the stupid names. I know that Henry the III (?) organized a big meeting during the investiture controversy to get rid of the whole 3 popes thing, and he appointed his cousin to be the pope, but I can't remember the things like, the meeting was called the Synod of Sutri, and his cousin's name was Bruno of Toul, but he changed it to Pope Leo IX.
And that's another thing, why do they all have to have the same name? It is hard enough trying to remember which pope did what without worrying about if you got the number right. Everyone is named either Leo, or Henry, or Charles, or William. What was wrong with medeival mothers? Obviously they lacked imagination when naming their kids. Did they not realize how hard they were making it for future students trying not to get the Leo who reformed the church with his own ecclesiaticals mixed up with the one who threw himself at Charlesmagne's feet 200 years earlier mixed up? Geez.