During file Import one has the option to Make a Second Copy To: and designate a location for a second copy of the photos being imported. I have so far used this - set to an external drive - but the other day it wasn't plugged in, and although I'm pretty sure the box to save a second/backup remained ticked, I received no warning that there wasn't any drive, and my import happened to the primary location only. So now I would like to add that import to the secondary location, but other than doing it outside of Lightroom (which is usually not a good idea), am not sure how.
I would think you could just select the photos and export using the export originals option.
I don't believe there is a link between lightroom and the second copy so I don't believe making the second copy with your OS would pose any problem. Just don't move the originals.
Excellent. Thanks for the timely reply..