Select an item (e.g. XXX);
Then click [Add];
(While the new item is still in editing mode) Name it with "YYY";
Press Enter (or Esc) key;
*One might not notice that XXX is still selected. So if you go on to change the options, or click [Delete], you are operating on both YYY and XXX.

Suggestions:
When [Add] is triggered, the other item(s) should be deselected.

And, while more than one item are selected, [Up] and [Down] buttons should be disabled.