system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: Why monarchs have numbers in their names to keep them distinct, why can't they have a different name?

like why king xyz 2 and not some other name
?
gpt
In most monarchies in Europe, the new monarch can choose their regnal title- basically their name as the reigning monarch, and quite frequently that's not their given name.

For tradition reasons, or because they want to evoke the image of a past and potentially revered ruler, they will frequently choose a name that's been used previously.

The Pope of the Catholic Church does the same thing on ascending to the throne of Vatican City.

It's mostly about tradition.