I right-clicked Applications -> clicked Edit Menu -> reset -> confirmed, but Ubuntu One, which I accidetanlly removed wasn't added.
Although Ubuntu One was removed, I tried to remove duplicated items in right-click Applications -> click Edit Menu -> Applications -> Others, but the duplicated items weren't removed.
How to solve these problems?
UPDATE:
I uninstalled gnome-menus and libgnome-menu2, because of the post at http://ubuntuforums.org/showthread.php?t=426204, but now Gnome App Central is gone from Applications menu.
