When Roman numerals were in use by the Roman Empire, the name of the Romans’ supreme deity, Jupiter, was spelled as IVPPITER in Latin. There was a feeling that using the start of Jupiter’s name on a clock dial, and it being upside down where it fell, would be disrespectful to the deity, so IIII was introduced instead.

newgateworld.com/…/should-it-be-iiii-or-iv-on-a-c…