From what I've read on other threads, I'm pretty sure that the second charger has to be coded as a slave in the firmware - not sure if the master also has to be coded to tell it it has a slave. Walter
Saghost, You are correct. I had a second charger added to my MS in April '13. After installation, the car had to be software configured to recognize the second charger. It did not happen automatically. I was present during installation, looking over his shoulder.