Question about a probably typo in descent of angels/fallen angels

Hey yall! I’m currently rereading the entire Horus heresy and I just got to descent of angels. This little detail bothered me SO much when I first read it but I feel I should ask the dark angels lovers. The master of training RAMIEL from descent. And the master of training REMIEL from fallen. What’s the deal?? I thought it was a typo at first but Michael scanton calls him Ramiel for the ENTIRE book of descent. If anyone knows plz let me know… are they the same person??? Did Ramiel take up a new name?? Is it someone else taking his name? Or is it one huge typo? Even on the lexicanum his name is RAMIEL. But when you click on the source it takes you to an angel from the 40th millennium