When I use my tablet pen to draw on the right side of the screen it will draw on the left side. It works fine as long as I don’t draw on the right side (except the pressure sensitivity does not work). The pressure sensitivity only works when I draw on the right side (which then shows it only on the left side). It does not act funny photoshop or any other software I have tried it with. I am only using one monitor and I have tried resetting my tablet settings (and nothings helping). I am only using 1 tablet and it is a Wacom.
First thing you should do is go to the top menu Edit>Preferences and under the Display tab change the renderer from Direct3D to OpenGL. Once done close the software.
Something else you could try is to reset your Drivers by using the application Tablet Preferences Files Utility from your Pen Tablet driver accessible from the Start menu. Simply remove all preferences and start the software after.