The double mileage counter indicates two different distances. To go from meter reading "A" to meter readings "B" or vice versa, press the switch. The odometer reading is doubled. Total mileage counter «A» (or «B») can be set to zero. Press the zero reset button for about a second when the counter reading is displayed "A". You can for example use one of the meters to calculate the fuel consumption and the other to determine the total mileage of the car.
Reset button for trip odometer data
Press the button to reset the counter data to zero.