Maybe this is a really dumb question and I'm not sure if this is the right subreddit for it but I'm assuming you folks here have the most expertise on this stuff.
So, kings who all share the same name. You'd think that you'd give the heir to your throne a name that would make him stand out, not be 'king number six'. It reminds me of people with pets who just call each new dog 'Sparky' or each new bunny 'Mister Sniffles'.
Obviously there are the Kings named George (which would make for a nice band name) and here in the Netherlands we've had a Willem 1, Willem 2, Willem 3, followed by a queen called Wilhelmina and at the moment we have a king again, called Willem-Alexander.
Also, if you don't use roman numerals to address the different Georges and Willems it looks even weirder.
But I digress.
Generally this occurred because you were trying to refer to a king who did something great - say King George is an illusion to St. George the dragon slayer - or that you were named after your father, which was very common even for non-royalty. Since these were the people most able to keep track of their ancestors, they would continue the same name for many generations, continually being named after their father (or close relative) before them.