Eli5: Why monarchs have numbers in their names to keep them distinct, why can’t they have a different name?

Question

like why king xyz 2 and not some other name
?

In: 72

Answer 1

They do have different names. Charles III is Charles Philipp Arthur George. “Charles III” is just his regnal monicker; his legal name is distinct from all other Charleses who reigned in Britain so far.