Hi, I just saw this and I am Serbian. The responses you got were so off the mark and ridiculous.
I have not heard of anyone called
Kleopatra (maybe gypsies would give a name like that, they have the habit of giving exotic names), but if a person existed and would have a nickname, it would be Kleo.
In no way would it be Klepatka or Klapa! These words sound horribly similar to other words ('patka means duck or bedpan, while klapa is a prop used in making movies).