duplicate contacts when syncing phone to car.....

I've not experienced any issues with my contacts on my iPhone 11 Pro that is updated to iOS 13.2.3. If you have not updated to that iOS, go ahead and do that. If you reconnect to Bluetooth in the car and it still will show duplicates, you may be better served talking to your Lexus dealer to see if they are aware of anyone else reporting problems, or they can assist you with troubleshooting the connection in their vehicle.

Are they duplicating on the iPhone, or just in the vehicle? In other words, after connecting to the vehicle, do the contacts on the phone show duplicates, or are the duplicates only showing on the iPhone? Does each contact only show a single contact piece, such as only one phone number? What kind of vehicle are you using?