Marc Davis fronm the user mailing list has provided a file (michael levine.pdf) that, when merged with another file, has a black image on page 17 ("TL-9"). I tried to investigate / narrow this somewhat:
- it happens with any other file, or just use the michael levine file twice
- extracting p17 with PDFSplit and then merging the result doesn't do it
- extracting p1-17 with PDFSplit and then merging the result does do it
- extracting p13-17 with PDFSplit and then merging the result does do it, altthough the black is now at the first page
The page is not really "black", the colors are incorrect.
That's all I found out until now. I compared the two files with PDFDebugger and can't see any obvious differences. I looked into the files with NOTEPAD++, there are some differences like that the colorspace is now indirect.