Share 'Swapping duplicate HDR environment problem'

I bought a sky HDR, and wanted to duplicate the environment I had set up using a free sample of it so that I wouldn't have to copy the settings over to it. So I duplicated the environment, changed the texture to point to the high-res HDR, and BOTH copies updated. Duplicate is supposed to make copies not instances, and there is no "Remove Instancing" available to 'unlink' them.