hi! not discouraging other responses, but there are a few comments in these post that can get you started
There were 16 French monarchs all named Louis, how was this tradition started? Has any royal line surpassed the French in repetitive names?
Why do many rulers have 'common' names with just a number to distinguish them? (e.g: Henry 1 to 8, Louis 1 to 18). When/where and why did this start and does it happen outside Europe?