The tab order on the edit item screen skips the add item button and goes up to the catalog search box, then the search submit button and then to the add item button after tabbing out of public note. It should go public note, add item, add and duplicate, add multiple, and then back to the search box at the top.
Sounds like Bug 12380, "can't tab to save buttons on add item." Pushed to 3.16.x for inclusion in 3.16.1.