From what I've gathered, the issue seems to be the driver not recognizing there are two displays and so the area it uses will only be half of your monitor. The easy fix to this would just to change the full resolution the driver uses by going:
Misc > (uncheck the "Auto" box for resolution) > (set "Left Offset" to 0)
Alternatively, you could just change the area to cover both monitors and that would solve the issue easily (i.e. if you have 2x 1080p monitors, instead of having area set to one monitor, set the area to cover both monitors) though you may have accuracy issue with your active area since you essentially doubled the pixels it will read in the X-axis
Misc > (uncheck the "Auto" box for resolution) > (set "Left Offset" to 0)
Alternatively, you could just change the area to cover both monitors and that would solve the issue easily (i.e. if you have 2x 1080p monitors, instead of having area set to one monitor, set the area to cover both monitors) though you may have accuracy issue with your active area since you essentially doubled the pixels it will read in the X-axis