Can't change form element names after copying them

[Computer Hater]

Hi,

I'm using Qt Creator's embedded Designer feature to design a form (on a Windows Vista Notebook).

After copying a group of elements (embedded in layouts) twice and deleting two of the copies again, one of which turned out to have been the original, I now have a group of elements being named "<original name>_3".
The original two instances are long deleted. At least they don't show up in the Object Inspector anymore (see screenshot). However, Designer won't let me remove the "_3" extension anymore. Every time I try, the name is instantly changed again as if the originals still existed. Renaming them to "_2" instead doesn't work either.

Any ideas ?

Edit:
Just before the problem occured I put the entire group in a new layout which I then deleted, intending to remove only the layout but thereby deleting all the contained elements. So I undid the deletion and cut/pasted the contents out of the layout instead before deleting it. I think I accidentally used copy/paste once and undid the cut/paste once as well.
After that I realized the names all had the "_3" extension, so I wanted to remove it - which didn't work.

Edit 2:
Closing and opening Qt Creator did the trick. But maybe still a bug with Creator ?