After you have paired the powermeter as a dual powermeter in the 4iiii App, you only need to connect the left powermeter (identified by ANT+ ID) to the head unit. The left powermeter acts as the transmitter to the head unit; it receives the data from the right powermeter, combines it with the data from the left powermeter and sends it as one signal to the head unit. The power data displayed on your head unit will then be total power (combined left + right) along with L/R balance.
