Yes and no. Two phone can be paired with one vehicle, but they will be treated as separate vehicles by the server. It won't screw anything up. Ben and his wife are my test case here, and we are able to tell which phone is on the car and keep the data and whatnot separate. This obviously breaks down if they are in the car together, since I can't tell who is driving. (Though come to think of it Ben does drive slower than his wife...) However, the data will not be aggregated otherwise, and the system will track the cars as if they are seperate.