ArabicMeaning
مَنْهُومَانِtwo intensely eager seekers
لَا يَشْبَعَانِthe two are not satisfied
مَنْهُومٌone intensely eager seeker
لَا يَشْبَعُhe is not satisfied
The ending ـانِ in مَنْهُومَانِ marks the dual: two people. The verb يَشْبَعَانِ is likewise a dual form. The narration then uses مَنْهُومٌ in each part to describe each of those people separately.
Reading the opening as a pair, followed by two individual cases, prevents confusing singular and dual forms.