Description of problem:
Certain steps lead to mistakenly displayed duplicate classes and that also probably causes bad tree refresh when a class is deleted.

Version-Release number of selected component (if applicable):
5.9.1.1

How reproducible:
always

Steps to Reproduce:
1. Create a domain and a namespace
2. Create a class (1) within the namespace that has both name and display name
3. Create an another class (2) within the same namespace, this time only with name and NO display name
4. Copy the class only with name (2) within the same domain and namespace, just give it a new name (3), safest way to do it right is to lock all domains except the one you work with right now.

Actual results:
The class with name and display (1) name can be seen twice in the tree - but not in the table on the right side.

Expected results:
No duplicate display

Additional info:
After you do this and delete the copied class (3) let's say, the class won't disappear from the tree although it gets really deleted.