It doesn't make any difference, it's not that you have two copies of the scenery installed, you only have two copies of the *uninstaller*, which is what the Windows Control Panel Add/Remove programs show.
So, by uninstalling everything, and installing only the most current version, the only change is that your Windows Control Panel Add/Remove programs section will look better, but the hard drive space used will be exactly the same, save for the few Kbytes taken by the additional uninstaller.