
X-Plane only supports one type of view (3-D cockpit, forward with no scenery, etc) at a time per copy of X-Plane.


In general, using multiple displays on one computer will be more restrictive regarding the ways in which you can configure the simulator. You can either have your monitors all connected to one computer, running one copy of X-Plane, or you can have multiple different computers all networked together, each one with its own monitor and its own copy of X-Plane. There are two general ways of configuring multiple monitors. This is straight from the X-Plane configuration instructions.

You cannot however, have three views (left, forward, and right) in 3d cockpit mode using one instance of the game. One instance of the game will allow you to have the instructor view or a 2d panel dragged aside on the second monitor. You need to be running an instance of the game for each monitor you want to power, assuming its a view of the plane or outside the plane.
