Hello,
Go to the top or bottom of a menu and press up or down arrow wherever you are, to hear the boarder sound. When you hear that, you will notice that NVDA will announce the item there twice rather than once.

This has previously been explained, but in short as I see it, this is because the first time the text is sent directly to the screen reader, and the second time NVDA reads the actual list item. This needs to be done because for example in Jaws, the list item wont repeatedly be read in this case and thus text needs to be sent directly. It's anyways a very minor thing.