A few bugs I encountered... I got some kind of error when I tried to do all 5xxx of them. It flashed so fast I couldn't read it.
I had been trying it on "screenshots copy" right in my folder.
I think possibly having a space in the folder name and then having "screenshots" in there also was the problem. I got a big problem when I ran it on "screenshots" -- it erased "screenshots copy"!
Also, it doesn't like spaces in file names either when there's both "filename" and "filename copy" in the same folder. (Seems to just over write files when you put the same .png file in the folder that already has the folder.)
I copied my "screenshots copy" _out_ of my MAME OS X folder and onto my desktop. Changed the name to "screenshotscopy", and then, no problems.
So, to make it clear - just doing "Apple-D" for you "backup" isn't good. I needed to rename the copied folder and take out spaces in the filename.
Thanks again for the tool!