This is a link to names given in Warsaw and they have been tracked since 2009. I believe they are taken from a particular paper.
http://gorny.edu.pl/imiona/index.php
You'll see that
Nadia is on the list at 53. The Russian nicknames
Natasza and
Sonia make the list as well. If you read down to the bottom you will see a few that do not conform to Polish spelling as well as some truly strange ones like Guantanamera (which they probably got from the song but which literally means girl from Guantanamo in Spanish) and Calineczka (which is Polish for Thumbelina).