Korriban was as it was known Pre-Clone Wars.
Istanbul was once Constantinople.
New York was once New Amsterdam.
Beijing = Peking
It happens in our world too.
So the Sith of TOR era know it as Korriban. The Jedi Council of Yoda's time know it as Moraband.
Except that it's referred to as Korriban in the books that came after the movies.