In the XProtect Smart Client there is no limitation. However, the number of secondary displays you can use depends on your hardware (display adapters, etc.) and your Windows version.

In order to allow the maximum possible viewing area, the title bar of a view sent to primary display or a secondary display is hidden. To show the title bar, and get access to the Close button, move your mouse pointer to the top of the view.

A carousel changes cameras at a specific interval, configured in setup mode. Example: With an interval of 10 seconds, the carousel will show Camera 1 for 10 seconds, then Camera 2 for 10 seconds, etc. The timing begins when you start watching a view containing the carousel. When you later begin watching the same carousel in another view, perhaps even in another window or another display, the timing for that instance of the carousel begins. This is why the carousel appears to be out of sync: in reality, you are watching two separate instances of the carousel. For more information, see Carousel properties.