nsajko
I have a LaTeX document. When I compile it with PDFTeX, I get this warning:
```
pdfTeX warning (ext4): destination with the same identifier (name{page.1}) has been already used, duplicate ignored
```
When I compile with LuaTeX, I get this instead:
```
warning (pdf backend): ignoring duplicate destination with the name 'page.1'
```
By searching the Web I can find multiple examples of other people getting that warning and some fixes, however, I'd like to understand what this warning actually means.
I have to note that I don't notice any visible problems with the compiled PDF, so I'm also wondering how safe is this usually to ignore?
Top Answer
Ulrike Fischer
Destinations are the link targets in a PDF.
## Targets to headings and environment counters
hyperref typically creates the names of such targets by using the counter name and the current number. If that is not unique, you get duplicated destinations. Warning of duplicate destinations with counter names like `section.1` should normally not be ignored as they led to faulty links. In the following example the second `\ref` jumps to section A and not to B:
~~~~
\documentclass{article}
\usepackage{hyperref}
\begin{document}
\section{A}\label{A}
\newpage
\setcounter{section}{0}
\section{B}\label{B}
\newpage
A: \ref{A}, B: \ref{B}
\end{document}
~~~~
The correct solution is then to provide a definition for `\theH<counter` that makes the destination name unique, e.g.
~~~~
\setcounter{section}{0}
\renewcommand\theHsection{appendix.\thesection}
~~~~
## Page targets
The special case of duplicated page destinations happens if a document uses the same page numbering twice. A typical culprit is the titlepage, see e.g. https://github.com/latex3/latex2e/issues/647 .
This warning is less serious as not many people actually use the page destinations but it means that the second page with number 1 is not reachable by outside links.
Typical solutions to avoid the warning, is to change the pagenumbering style (this also has the side effect to improve the page number in PDF viewers:
~~~~
\documentclass{report}
\usepackage{hyperref}
\author{me}
\title{some title}
\begin{document}
\pagenumbering{roman}
\maketitle
\pagenumbering{arabic}
\chapter{abc}
\end{document}
~~~~
another option is to suppress the targets with the `NoHyper` environment:
~~~~
\begin{NoHyper}
\maketitle
\end{NoHyper}
~~~~