I've had this issue before. I used to take the individual page pdfs that a colleague made and combine them into one pdf document. Acrobat started duplicating the pages. Instead of a 24 page document, I'd end up with 48 pages. On another forum, someone suggested that to avoid this, I export the pdf directly from InDesign. This worked, for a while.
Now InDesign has started doing this too. I specify that pages 1-24 be exported but I still end up with 48, all duplicates. Most of them are tacked onto the end of the pdf.
Any suggestions would be helpful. Thank You!!
Does your document have an alternative Layout?
Nope, just the one.