I think OP misunderstood the Chinese Dual citizenship policy
Theoretically, After acquiring Second Citizenship, your Chinese citizenship will be lost.
However, in the reality, the Chinese government has no way to check if you just get your second citizenship and having a second passport does not make your Chinese passport invalid immediately. The passport will still work as long as it is not expired.
The only way they will know your second citizenship is by you surrendering your Chinese passport. It usually happens when a former Chinese citizen would like to visit China. In order to do so, he needs a visa on his second passport. Chinese embassy will ask for those who born in China surrender their Chinese passports before the Chinese visa is issued.
Another point needs to be noted is that
If a Chinese citizen who acquired Second Citizenship try to enter China with his Chinese passport, there is a very high chance for Chinese custom will know he/she has a second Citizenship.
For those Chinese citizens who residing in U.S/Canada or some major Europe countries, if their Chinese passport has no valid residential visa of those countries they are living nor can they provide permanent residence documents of those countries, the custom will make further inspection on those people and ask them to surrender their Chinese passport.
Unless some Chinese citizen can get a second citizenship without being actually live long term in that country (such as certain investment passport program in some Caribbean islands nations), there is no way to get around this. You either keep your Chinese passport and don't enter China for the rest of your life, or you just be honest with the embassy and get a visitor visa.
The only exception I can think of is Chinese citizens born in Canada/US and when they are born, their Chinese parent/parents cannot be foreign permanent residents in any other country. (The Chinese parent/parents can hold working/study visa or visitor visa however). Under this circumstance, the Chinese citizen born in Can/US can hold their Chinese citizenship and get Chinese travel documents from the local embassy. In the meanwhile, they will hold Canadian/US passport because it is their birth rights. So those minors can enter China as Chinese and enter Can/US as Canadians/Americans. Such "dual citizenship" can be maintained until minors turn to 18. After that, they have to choose either Chinese or Foreign citizenship.
Frankly speaking, it is pretty sad for us because I know a lot of European descendants who hold multiple passports from their parents and their grandparents. Even Citizens from the Republic of China(Taiwan) can still pass down their passports for generations without going back to Taiwan. I would love my children and the children of my children still hold some heritage to remember.