Basically, there is a fundamental difference in the way the two communication protocols operate. With ANT+ the pedals are connected to each other in a master/slave relationship. The pedal that serves as the master, the left in our case, connects to the display device as well as the slave pedal and does the lion's share of the work.
For BLE (Bluetooth Low Energy or Bluetooth Smart) each pedal is paired individually to the display device and it is up to the display to combine the two power values. If a display device does not have the ability to pair to two individual power sensors (most do not) a user will see ½ power. Unless that display device has some built in smarts to double the value when only one pedal based power meter is connected.