Copy/paste doesn't make category item filename unique

When item, e.g. product is copied from one category to other category, then it's Filename field's value stays the same. I suppose this happens because of maybe category item's filename should be unique only inside it's primary category OR Filename's field unique value just not updated during copy/paste operations.

When I edit such category item (the one I've just pasted to other category) and without changing any of the fields save it, then "_a" is added to it's filename resulting all detail page links on Front-End to be invalid.

I suppose, that "_a" should be added during cloning.