[dllthomas]

While it should not be possible for the software to decide to turn on a conflicting configuration of lights, it is possible that something was mis-wired or mis-configured (consistently between the monitor and the control system, if it was in fact set up the way it should be, per lexicalscope's comment) such that the monitor and control system were not aware that that configuration of lights was dangerous. There is nothing inherent to the physical configuration of wires and colored glass that will mean "left arrow on side B" to a microcontroller.