Ordrang and Molg are evidently members of the same species, being the female and male of the species, respectively.
Sexual dimorphism is weird.
As few gain access to the chambers of Remegni the Stoic, no one knows if his survey of the Molg life cycle has uncovered this fact. Depending upon how the sexes are established (no one knows for certain), it is possible he will never observe the behavior, or maybe he just wonders why Ordrang keep getting into the habitat.
The course of occult science rarely runs smoothly.