Ok so here is the problem. I have an archive of approx 6000 pdf's. At one point I ran OCR on them using adobe with the output saved to a new folder with files named PostOCR-filename.pdf For some reason the folder of post OCR files is 12 files short of the original pdf file count. I want to keep only one copy of all files. So basically I want to keep the PostOCR files, plus the 12 unknown files that weren't OCR'ed. The problem is - how do I identify those 12 files ? I mean I could open 2 finder windows and drive myself demented manually searching for them - but I figure there must be a smarter way. Anyone have any genius quick and easy ideas ?