At the end of the update, MBUX writes: restart the system. If you have done that, you have installed the latest update/map.
Doubt it wrote that it uninstalled the last update, mine also came with an error/warning when I removed the usb. If you look at map versions, you can see the latest ones further down the list.
A bit strange that it is not at the top of the list..
As far as I know you can always install the update again if you are not sure.
As long as the usb is in the car, it will say there is a map update even though it is updated.