They are duplicated for convenience. They probably don't add much convenience when accessed from the right-click menu, but in other contexts (such as the "Add Surface Layer" button) they might.
By the way, I see that your sub-menus are opening right to left, which is unusual. I have used a couple of computers where this happened, and I'm not 100% sure why but I think it may be related to Wacom drivers. Do you have a Wacom installed, or do you know of any other reason why they are opening this way?
Matt