Although the simplest explanation, that it's simply a resued name (in the same way thousands of towns and cities on earth are endlessly duplicated), is good too.
TOS/TAS had two Arrets: Sargon's planet of origin ("Return to Tommorrow") and Karla Five's homeworld ("The Counter-clock Incident").
TAS had Edos and TNG had the Edo.
There are several species of Rigellians/Rigelians and lots of Rigels.
I'm sure there are other similar duplications.