They are devices that are not properly included. When this happens, the correct thing to do is:
a) Exclude the device in question.
b) Unpower the device in question.
c) Remove the ghost as detailed by @Sebastien.
And then proceed. Inclusion for z-wave devices will only work if the device communicates directly with the controller (hub), so they should be in close proximity to the hub. Z-Wave+ devices support "network-wide inclusion", so they can be included through a repeater. However, unless you have a very robust z-wave mesh, I would recommend including these devices in close proximity to the hub.
In both cases, you can run a device-specific z-wave repair after the device is in its final location.
