Since the Russian citizen will have a Schengen visa - you do not need to open a Croatian visa, you can enter Croatia on a Schengen visa.

Important point - for such a trip the Schengen visa must necessarily be multiple (that is, the possibility of multiple entry and exit to the countries of the Schengen agreement) The visa must be marked MULT.

Yes, a Schengen multiview citizen of Russia will be able to enter, but with the fact that the visa was redeemed by the state issuing the visa, or if there is a voucher of stay in the country that opened the visa, so that at the border it was possible to show why the visa was opened.

Read more on the page "Visa to Croatia" .