"This is proof that these cloned letters are not evidence of tampering, but in fact a product of the OCR scan".
Depends on what you consider OCR. There's been a pile of confusion on this subject. And there would be no reason to use such a program on this COLB
Bottom line is this doc has so many things wrong with it, it defies logic.
Even if you take a small chunk of text, though, you will still find repeated letters at about the same distribution as the Obama birth certificate. For example, looking at just the first line of the first Korea document (1952-01-03a.pdf), the o's in "South Korea" are identical to the pixel, as are two of the three e's in "revealed."
I still think this is a common occurrence in PDF files of document scans, particularly those that have some enhancement to the text, be it OCR or something else. It's common enough for me to conclude that it is not a sure sign of tampering.