a new device joined your network -- maybe misidentified?

I got an email from Xfinity yesterday saying a new device joined my network.  It was identified as an iPhone.  I used the Xfinity app to investigate.  the app claims the device is currently connected to my wi-fi network, and I can see its MAC address.  The MAC address doesn't correspond to the MAC addresses of any of my devices, including the iPhones I have.  I used the app to pause the connection to that device.  When I did that, one of my iPhones (again, with a different MAC address) was unable to access the internet (cell service is almost nonexistent at my house, so I know it was trying to use wi-fi).   When I unpaused the device, my iPhone was once again able to access the internet.

When I look at the devices connected to my home network, I see that one of my iPhones is listed as connected and one is listed as unconnected, even though it is in fact connected.  So it looks like the Xfinity app, or the infrastructure behind it, is thinking that one of my iPhones is a different model of iPhone with a different MAC address.  I don't have any problems using my iPhone, even with the identity issues.  But it is kind of weird.

I've talked to tech support, and they think it might be a glitch in the system.  But I thought I'd post here to see if anyone else had a similar situation.  Maybe that will encourage Xfinity to get the problem fixed sooner.  I really don't want to keep getting false alarms.  It might make me less vigilant.