Dual citizenship came into the Russian law only 25 years ago with the Article 62 of the Constitution of Russia giving the right for dual citizenship for all Russian citizens.
Federal Law on Citizenship of the Russian Federation was adopted in 1991 and completely revised in 2002 providing information on the differences between ‘dual citizenship’ and ‘second citizenship’. The dual citizenship is possible for Russians on the ground of international agreement. Russia has concluded a few international treaties which contain provisions related to the dual citizenship, while all other cases of obtaining foreign citizenship is considered as second citizenship.
Concerning second citizenship, the Russian Federal Law does not prohibit it, however it is subject to restrictions and control. The acquisition of another citizenship by a Russian citizen does not entail termination of the citizenship of the Russian Federation, and persons who obtain the second citizenship need to declare their second citizenship to the Russian bodies of migration control within 30 days, in accordance to the Citizenship law amendments of 2014.
Source: Investment Migration Council, Paul Kalinichenko