APID is an ID generated by Urban Airship. It has nothing to do with the IDs you already have. When you use their API, you'll get an APID for each device.
An APID (Airship Push ID) is the unique Urban Airship identifier required in order to push to an Android device via our API. Each new installation of an application generates a new APID, so if you uninstall and then reinstall the app, it will get a new APID for that app.
You can read more about it here.