@kilowatts it could also be a bad device creating a ghost device and could be indicating a cause of other problems. The only way to be sure is to power down 1 device at a time and do a fresh scan each time.
@Rxich spectrum analyzer can also be useful to check for noise on your network and you can adjust your wifi settings to improve it as well as showing you which zigbee channel to choose if you are having issues with devices falling off.
