Hi Paolo,
I just merged a couple of documents using version 2.0.2009.701 and, on the output file, a logo from the first page of the first document was suddenly changed into a reversed image. When I use "preview this selection" it also shows the logo in reverse image. However, when I view the original document using the Adobe reader, it appears normal.
I am using the Adobe Reader version 9.3.0.
The original document's properties say that it was produced with PDF version 1.4 (Acrobat 5.x).
If you want, I can send you a copy of the file.
Larry