thapap, Yes, there are chettri bistas like Dor Bahadur Bista and Keshar Bahadur Bista. But, Kirthinidhi Bista is a Bahun Bista.Bista, Pathak, Panta, Tiwari , Joshi, Pandey are common Bahun surnames not only in Nepal but also in the Kumaon Garwal - Almoda region.