Expatriation.
Yes, it is called dual citizenship.
Emigration is the act of leaving ones natural country for residency in another country. Immigration is the act of leaving ones natural country for citizenship of another country.
If they do not have the citizenship of any country as a result of renunciation, then they are called stateless. **Some people mistakenly confuse stateless situation with expatriate. Expatriate means when someone lives in a country other than the country(ies) of their nationality(ies).
A resident
naturalized citizeens
You don't have membership of a country as such. People are citizens, not members. So you have citizenship.
people who are born there and who have citizenship are known as Emirati's. People who only work there, but who have citizenship in another country are called expatriates.
A foreign person that is admitted to citizenship is called 'naturalized. ' Before that they are know as '(home country) nationals' and they hold a what is called a green-card.
Whatever citizenship it may be, the basic responsibility of any citizen would be to uphold the principles of the constitution of the country and render service to the country when called upon to do so.
If both your countries of nationality require a visa to enter the destination country, then you should obtain a visa and have it stamped in one of your passports prior to your departure. If the country of destination is one of your countries of citizenship, then you should just use their passport.
A country that is a 'friend' of another country is called an ally.
When you leave a country it is called emigration.When you arrive in a country it is called immigration.