This is normal. The system does pair with more than one phone, but will only be connected to one at a time. To change to the next phone you need to use the voice command "NEXT PHONE".
Mine seems to remember the last phone connected and connect that first if more than one phone is present - eg. My wife and I are in the car and the system is connected to my phone... we leave the car and return together and it will connect to mine first. We go away again and she come back to drive on her own - it connects to hers. Later I return with her and it will connect to hers first. (I then use the NEXT PHONE command to connect my phone)
Does this make sense?
I know what I mean (I hope I explained it)