Adobe lightroom problem on export
If you want to take a file back to the original unedited on in Lightroom all you have to do is pres the back slash key, "\" or you can simply go to the history and click on the original import. You can then make a virtual copy and start all over. Once you make the virtual copy then press "\" again or click on the last entry in history to return your file to the edited version.
Of course the easiest way save copies of the original unchanged RAW file is to copy them before you start post processing them. If you want copies of the original unchanged RAW files after post processing you can easily get Windows Explorer to arrange the files by type, i.e. all the RAW files will be listed then all the XMP files. Select only the RAW files to copy.