It is possible that Harshavarman III has been succeeded by a king named Nripatindravarman which reigned in Angkor until 1113 and that Jayavarman VI never reigned there.
In fact Suryavarman II claimed to have seized power from two kings; one is his uncle Dharanindravarman I of which there is no inscription in Angkor; the other can only be Nripatindravarman.
References
Nripatindravarman Wikipedia(Text) CC BY-SA