@irandamay - I have no idea how even installing "two copies" of the plugin is possible? You haven't been experimenting by writing your own plugin and copy/pasted in the Goodreads plugin name or something? Can you think of any other metadata download plugins you installed recently that were *not* by me?
Go to Preferences -> Miscellaneous -> Open calibre configuration directory. Bring open the plugins subfolder. Delete whatever Goodreads zip files you have in there (You can ignore "Goodreads Sync.zip" if you have it installed as that is a safely different plugin). Restart calibre and look at the list of plugins you have installed - does it still show Goodreads? If not, now install the Goodreads plugin again and you should be fine.