Similarities in the Saints

Each day in my class I write the names of the day's saints from Lives of the Saints volumes I and II on the board. Something that I have always noticed is that the saints who share a feast day very often have some remarkable similarities (I am not even talking about those who are grouped together on the calendar).

For example, last week St. Augustine and St. Moses the Black shared August 28, and both lived lives of terrible debauchery before turning to Christ. Today St. Rosalia and St. Ida are both descendants of Charlemagne although from the 12th and 9th centuries respectively.

It always makes me wonder if there is anything more to it in God's plan.