Dual American Citizenship (USA)
The American immigration policies discourage the dual citizenship in many ways. However, the governmental organisations tend to allow it but do not want to officially acknowledge the dual American citizenship. There might be some restrictions on people with dual American citizenship such as the requirement to enter the USA border with the American passport not with that of another country.
As you can see, there is no proper regulation for dual citizenship in USA. But generally speaking, it is unofficially accepted by the American government.