(OS/X El Capitan ... MacBook Pro)
From time to time, when I go to *System Preferences...Network...WiFi...Advanced," I find that two network-names have been added to the list without my knowledge or consent:
How do I know this? Heh ... "Because I happen to live in a hole." That is to say, "a little corner of Northwest Georgia (USA)" where there is exactly one wireless network: "Mine!" I work from my home, so my computer rarely leaves it.
I have turned off "Remember networks that this computer has joined," and in any case I can positively say that this computer has never encountered, let alone "joined," either of these networks.
So ... what's going on here?!