According to Article 5 of the Penal Code regulations:

Article 5. Effect of the Criminal Code on criminal offences committed within the territory of the Socialist Republic of Vietnam

1. The Criminal Code applies to every criminal offence committed within the territory of the Socialist Republic of Vietnam.

It also applies to criminal offences committed on sea-going vessels and airplanes having Vietnamese nationality or operating in Vietnam’s exclusive economic zones or continental shelves or consequences thereof.

2. Criminal liability of foreigners who commit criminal offences within the territory of Socialist Republic of Vietnam and are granted diplomatic immunity according to Vietnam’s law or under an international agreement to which Socialist Republic of Vietnam is a signatory or according to international practice shall be dealt with in accordance with the international agreement or practice. If the case is not set out in any international agreement or there is no such international practice, their criminal liability shall be dealt with in a diplomatic manner.

Accordingly, people who commit crimes on Vietnamese territory will be handled according to Vietnam's Penal Code. Therefore, having two nationalities and one of which is Vietnamese will automatically apply the Vietnamese Penal Code.

In cases where the offender is subject to diplomatic or consular immunity according to Vietnamese law, international treaties to which Vietnam is a member, and international customs, criminal liability will be resolved according to the law. that international treaty or international practice. If an international treaty has no regulations or international practices, it will be resolved diplomatically.