WarningDocument Structure
Label Multiply Defined
LaTeX Warning: Label 'XXX' multiply defined.
What this error means
Two \label{} commands in your document use the same identifier. LaTeX will use the value from the second definition, which may cause wrong cross-references. This is a warning, not an error, but the output will likely be incorrect.
Common causes
- The same label string used in two different \label{} calls
- Copying a section and forgetting to rename its label
- Multiple included files each defining a label with the same name
How to fix it
Give each \label{} a unique name. Use a naming scheme like fig:plot1, tab:results, sec:intro to avoid collisions. Run LaTeX twice after renaming to clear the stale .aux file reference.
Code examples
Causes the error
\documentclass{article}
\begin{document}
\section{Introduction}\label{sec:intro}
% ...
\section{Background}\label{sec:intro} % Duplicate!
\end{document}Fixed
\documentclass{article}
\begin{document}
\section{Introduction}\label{sec:intro}
% ...
\section{Background}\label{sec:background} % Unique label
\end{document}Related errors
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