For the line of ascension to make sense, I think that Thondraw's dates were supposed to be Mergante's (although his are not noted on that tomb), and Thondraw's should be more in line with Lyriden's.
Listed in Scores & Achievements:
Under Impious Princes:
Darthenos is listed twice
(along with Khornil and Nengorth listed once)
Forget the name of the one that is missing.
Under The Royal Mausoleums:
Queen Lyriden is listed twice.