My understanding is that the day you accept the second Nation's citizenship your Nepali Citizenship is automatically revoked. Now, some of you might have been under impression that as long as i have my nepali Passport i am a citizen but not according to the Nepali Law. Once you accept foreign citizen you are no longer a Nepali Citizen Legally. Lets say you get into the legal battle in Nepal and your nepali citizenship is on question, then they will say the day you became foreign citizen you were no longer a nepali citizen.

I do not know what the proper admin process is to denounce your citizenship in Nepal but i would not be under assumption that just because i am holding a Valid Nepali passport you are a nepali citizen as well. In Spirit you can always remain Nepali but by citizenship you are no longer one once you accept another citizenship.