Rod,
when you unzip a .zip version likely you get a folder with the same name of the .zip file.
If you look into that folder you discover it contains another folder with the specification of the release.
By using this latter you avoid duplications and you do not need to remove previously downloaded/unzipped folder, having different names, so that you can point in Gimp preferences directly and only to the release you last downloaded.
Example:
I downloaded the file gmic_gimp_qt_win64.zip
After unzipping I got the folder gmic_gimp_qt_win64
By looking into it I found the folder gmic-gimp-qt-2.0.2-win64

I used that last one to move to Gimp user folder.