Sometimes I get double WiFi indicators on bottom bar (Redmond theme). I have identified so that one of the WiFi icon is on "Notification Area" applet and another is in "Indicator Applet complete".
If I switch my appearance and return back it usually fixes the issue.
I had this issue the other day for no reason, I killed and restarted nm-applet and it fixed it, the icon disapperad from the systray to be only in the indicators area, as expected:
killall nm-applet
nm-applet &
exit
Does it happen frequently for you?
Not very often, but it happens time to time on my Lenovo and Dell laptops.
I think this might be related to situation when Laptop is not able to connect to WiFi and there is this notification pop-up saying “no internet bla bla” and almost on same second I get connected to internet… after that almost always I have double WiFi icon.
Rebooting is not helping, but I have to switch Theme. I will try those commands on next time.
This is a known problem in all the ubuntu flavors. In 18.10 the problem in my opinion will be fix because of the backend switch