Hello, again.
We are seeing an issue when the PdfDocument.MergeFiles(Stream[]) method is used to merge two PDFs together. When the saved PDF is opened in Adobe Acrobat Reader, it looks fine, but Reader will prompt to save the document when it is closed. I have rewritten our merge code to create a new PdfDocument and add the other PDFs using AppendPage(PdfDocument) instead and the resulting PDF is fine.
Attached is a zip file with a source PDF file (linq.pdf) and the result of merging that document with itself using MergeFiles().