Bug #11862 has finally been fixed, thanks a lot!

However, now I experience the following issue with the latest git code compiled:

Let's have a folder named "folder.foo" and a file called "file.foo"

Duplicate both will now result in: 
"folder.foo (Copy 1)" and "file (Copy 1).foo"

Now create another copy of the original folder and file:
"folder.foo (Copy 1)" and "file (Copy 2).foo"

The folder won't duplicate because the numbering won't be checked, it will try to create another "(Copy 1)".