The book class (and its friends and relations) automatically changes the display of page numbers in the frontmatter of the document to lower-case roman. This is fine for human readers, but if hyperref has been misconfigured, the existence of pages have the same page number can cause problems. Fortunately, the configuration options to make hyperref “do the right thing” are (by default) set up to avoid problems.
The two options in question are:
\thepageto the PDF file so that Acrobat Reader can display the page number as (say) ‘ii (4 of 40)’ rather than simply ‘4 of 40’.
The recipe isn’t perfect: it relies on
\thepage being different
for every page in the document. A common problem arises when there is
an unnumbered title page, after which page numbers are reset: the
PDFTeX warning of “duplicate destinations”
will happen in this case, regardless of the options.