I use the sample file "DeviceDisconvery.py" to scan the network,at the second time,it returned the same devices twice

[chandlergee]

[JoelBender]

Please check the traffic using Wireshark or something similar, you'll probably find that router to network 20 may be responding as a proxy for the other devices and also forwarding the I-Am responses when they are available. The network traffic may also show that the router and/or devices periodically send unsolicited I-Am messages, and check to see if there is a different BVLL message type, unicast or broadcast.