The link is working, but I am surprised if this proposed fix actually does work.
I also had two Sophos shield icons in my Finder menubar under Mountain Lion, because there were two instances of Sophos UI Server running.
The second instance was created by a Login Item for my user account, which I deleted as suggested by other users posting in this topic. Note that you have to unlock the Login Items preference pane, and remove the problem item from the list with the [ - ] button. The checkbox to the left of an item in the list has nothing to do with enabling/disabling it.
The preferences file at <~/Library/Preferences/com.sophos.ui.plist> is unchanged by this action. By a reading of its contents, that plist file does not appear to have anything to say about launching a duplicate UI Server process.
