The nVidia driver seems to be treating the two 1920x1200 monitors as one 3840x1200 monitor. This resolution is then not supported by the X Server, causing the error message. However, the display still works as expected.
The nVidia driver seems to be treating the two 1920x1200 monitors as one 3840x1200 monitor. This resolution is then not supported by the X Server, causing the error message. However, the display still works as expected.