Folks Complain About the French Overusing Louis but man...
For a few short years around 1210 CE 3 of the Christian Kings of Iberia all had (essentially) the same name. Alfonso VIII of Castile was a cousin of Alfonso IX of Leon, and Alfonso IX would marry Alfonso VIII's daughter Berengaria. Afonso II married another of Alfonso VIII's daughters, Urraca - making them all one big confusingly named family.
Though this idea of overusing royal names is hardly unique in medieval history, this is one of the most confusing cases I can think of.
And stuck in the corner, left out of the party is the King of Aragon, Peter II. Who is not nearly as interesting or impactful as his descendant Peter III. #history