Firefox is installed twice in 'program and features'
I installed 27.0 from 26.0. Basically i updated it through the setup. When i saw the list of installed programs in my Control Panel , there were two instances of the 'Mozilla Firefox installed'. One was the firefox 26.0 and the other 27.0. What does that mean? When i try uninstalling the older one the newer one too gets uninstalled.
Must have been a phantom registry entry for the older version, something that Windows is renown for doing.
Then is firefox into something to fix it.
You installed Beta Firefox 27 over Firefox 26 (Release) without changing the installation directory (via Custom Installation), so Firefox 26 was replaced by 27. Windows should have changed the original Firefox 26 in the Control Panel instead of adding a 2nd listing for Firefox 27.
If two separate programs aren't installed, is that Mozilla's fault, when in fact only one version remained installed?
I changed the installation directory to D: instead of the system directory C:. But still the problem persists.
What you have is two separate programs named Firefox. You should check the Programs Remove window via Windows Control Panel.
You could also try cleaning up your registry by using glary utilities. It does have a registry fixer as well as some other utilities for uninstalling programs you might want to look at.
Just go to http://ninite.com/ then in the middle column under utilities choose Glary. Then choose get installer at the bottom, then if you have the option to just run it or save then run. This will set up Glary for you without any interaction and will NOT install any toolbars, or any garbage like that as well