I think it is because the remote display is using AirPlay technology which in my experience, has only ever replicated a single screen. I use the Immersed app in Meta Quest 2 and 3, and it has a client application that goes on the desktop/laptop and uses a proprietary method to replicate and create additional displays. On Immersed's Discord server, there was a post that they are working on this for the Apple Vision Pro (AVP) . I would love to see native support from Apple though, and also methods of connecting to other devices, such as PC, phones and tablets. As there are some apps in the store that are available on iPAD, but not on AVP, connecting to an iPAD would be very useful.