Hi
I did have a conversation with a IT specialist some time ago who explained that windows 8 by default will look for any wireless device within the range of your router or adapter and will pick up on any device within range informing you of a wireless device
in the vicinity of you wireless area weather you have mac filtering or what ever your protection is it will show. This does not mean that this device is in you network it just means that, that device is there and with out the right password and stuff it cannot
connect to your network which can be verified by trying to add the said item to your network and as with my attempts as I am sure with your attempts none of the offending devices can connect to my network as a profile is unobtainable meaning this wireless
item is there but unable to connect to my system. Which can be verified by turning off all your PC's phones tablet and any thing that is wifi in your network and observing your router's up and down stream lights on your router. You should get the twenty or
thirty second blip that all router's send out and not a lot more.
If there is constant activity then you need to worry about your system security and perhaps a further investigation.
Hope this helps it certainly did with me.
dg38dg