No, it is not so. A marriage is certified not by a stamp in a passport. In case you register a new marriage without dissolving the previous one the new marriage will be hold invalid (Art. 14, 27 of the Family Code of the Russian Federation). According to Art. 158 of the Family Code of the Russian Federation marriages concluded between Russian citizens and foreigners in the territory of foreign countries in accordance with laws of such countries are legal in the Russian Federation in the absence of impeding circumstances. According to Art. 160 part 1 of the Family Code of the Russian Federation marriages between Russian citizens and foreigners are dissolved in the territory of the Russian Federation in accordance with the Russian legislation.