Don't see how I'd be picking it up unless it was on the same network as me. (I'm at home, admittedly in a flat with people in all directions from me, but on my own network with a non-trivial wpa2 key)
If it wasn't for the first one showing up in my router config I'd happily believe it was just windows being odd. The weird thing is that all four devices have had different Mac addresses though. Very strange.
Yeah, if it was all one MAC address I'd just put it down to Windows being a dick.
Our phones have never shown up (Galaxy s4 and a Oneplus One). It's weird cos these things only show up for a second, if I refresh the page they disappear immediately.