as posted by @capsat
"The accelerator pedal position sensor is mounted on the accelerator pedal bracket. The accelerator pedal position sensor has 2 sensor elements and 2 signal outputs: VPA and VPA2. VPA is used to detect the actual accelerator pedal angle (used for engine control) and VPA2 is used to detect malfunctions in VPA. When the difference between the voltage outputs of VPA and VPA2 deviates from the standard, the ECM determines that the accelerator pedal position sensor is a malfunctioning. The ECM turns on the MIL and the DTC is set."
VPA and VPA2 are 2 redundant signal outputs just to ensure that ECM is reading the correct value, when VPA and VPA2 outputs deviates the ECM considers it as a faulty Pedal sensor