I think, it depends on Windows version and auto-complete behavior setting. FWIW, Windows 7 doesn't do this with default setting. I do, however, recall observing this kind of behavior on XP.
It definitely still happens in Visual Studio on Windows 7, not sure about other places. Resharper might change this behaviour, not sure as I don't currently use it.
Nothing beats accidentally creating a new class instead of adding an existing one as a reference just because your cursor was in the wrong place, then spending time on wondering why nothing happens.
