grogache

It varies a great deal. In my case it took 25 days to get from "NVC receive" to the interview at the embassy. Also, we only received an email from embassy saying that we can schedule an interview online. We received no paper letters neither from NVC nor from embassy.

Russia just doesn't acknowledge the other one if it doesn't have an agreement with the other country. So for the purposes of Russia, as far as i understand, if you only show the Russian passport they don't care that you're also a US citizen and treat you as if you were just a Russian citizen.

I wonder if it was the EU side that made her drop it then.

This is exactly right. If you enter Russia using russian passport you are considered Russian citizen for all legal purposes and all your other citizenships do not matter while you are in Russia. There is nothing in Russian laws that forbids you to have another citizenship. It is simply not recognized and you are not considered to be "also US citizen". You are 100% russian citizen while in Russia if you entered the country using russian passport.

I am naturalized US citizen and retained my original Russian citizenship. I've traveled to Russia to visit my fiancee, family and friends several times. Entering Russia I just show my Russian passport and I do the same when I leave Russia. So, my US passport does not have any stamps from the Russian border control. However, you still need to show US passport at the airline checkin and at the border control when the officer asks you about US visa.