I could, but I need also to include also jpeg and tiff images. After a quick look, I had the impression that CAM::PDF does not support jpeg and tiff, but I may be in error, of course.
Besides, I am not sure that this is a bug of PDF::API2. It could be an Acrobat's problem or the result of a malformed .pdf file. Unfortunately, I have no control on my source files. Interestingly, I tried to combine the two source .pdf with Acrobat pro 9 and it also fails, but in a different way. I tried also pdftk and found that it behaves in the same way as Acrobat pro.
I may have to convert the .pdf into bitmaps and include them as such, but it seems a pity.