I *think* from what we've been told that the H Plus camera will be running different firmware from the H520 equivalent. So it's pretty unlikely the H Plus controller will be able to dual operator the H520 camera (if you see what I mean). The suggestion is that the H Plus camera firmware will be compatible with the old Typhoon H, so it may support dual operator - but the ST-16 that comes with the H Plus has different software from both the H-520 controller and the Typhoon H, so it may not have a 'dual operator' function built in. You may be able to dual operator the new camera for the Typhoon H and H Plus with an old ST-16 running the Typhoon H flight stack.
In other words... there are a few different combinations of controller and camera, and there's no evidence yet which will work and which wont.