:focus:
Getting back on -topic,
IMHO The original screenshot shows not users but Devices, the home routers that most users are provided with by their ISP use a small range of standard Network segments [SubNets] such as 192.168.0.0-255 or 192.168.1.0-255 which are part of the standard Private segments [these are blocked on the wider internet so only identify local devices.
What happens in a local area is several users [at household / small Medium businesses], all end up using the same default segment. this results in all the devices on all of the identical network segment addresses showing on all the routers within communication range of each other.
The simple way to prevent this, [assuming the ISP allows the user access to the Router settings or you use your own], is to change the third segment to a less popular number than the 0 or 1 used by ISPs.
Eg. change the Segment address to 192.168.50.0-255 should remove the phantom devices.
Although the various devices will be visible on both networks that have the same segment addresses the passwords for access should prevent unwanted access to the devices on other networks.
There will be usually be more phantoms visible in a high density area such as a City or close to a small business that in a rural or small town area