Nie wiem czy to nadal się praktykuje, ale w 2012 można było znaleźć bez problemu informację, że jeśli pojechaliśmy do Kosowa (niepodległość ogłoszona w 2008) i dostawaliśmy w paszporcie pieczątkę Kosowa to później kontrola graniczna w Serbii je anulowała.
Serbia does not recognise Kosovo as an independent state, nor does it recognise the Kosovar passport as a valid travel document. However, citizens of the Republic of Kosovo can freely enter Serbia and stay for 90 days with a valid identity card.
When the issuing of new Kosovar visas and passport stamps began in 2008, Serbia refused entry to people with entry and exit stamps of the Republic of Kosovo customs authority stamps or visas in their passports. In addition, border crossings from third countries (Montenegro, Albania, North Macedonia through land, many more through air travel) to Kosovo were considered illegal points of entry by Serbia, and it had created problems if one entered through there and then attempted to leave Serbia through another border crossing in Central Serbia or Vojvodina without a corresponding entry stamp. That practice, however, was soon abandoned and these are now simply over-stamped (nullified), which potentially could create new problems with long term Kosovar visas being annulled.