Before you start to use the dueling feature in "Airplanes, Etc." you must pair your two devices. This requires that you go to your SETTINGS program, go to the Bluetooth section, enable device discovery on your phone, and then actually pair with the other device.
When you do this a small dialog will open on the other device asking if they want to pair with you. You must say 'yes'. After that the "Airplanes, Etc." Dueling screen will show the paired device in it's Bluetooth device list.
More detailed instructions for pairing can be found on line.