We figured they are eligible for renewal because they had the same class of visa before.
https://www.ustraveldocs.com/in/en/renew-visa
Eligibility criteria for all applicants, except children under 14 years of age and applicants 80 years of age or older:
I have a previous U.S. visa in the same class as the visa for which I wish to apply. Not applicable for F, H-1, H-3, H-4, L (individual), M, O, P, Q, and Academic J (Professor/Research Scholar/Short-Term Scholar/Secondary School Student/ Teacher), who were previously issued any class of visa.