# Printing the bibliography twice?

I am preparing a paper submission to a conference that wants two PDFs:

• A main paper
• A supplementary material section (e.g. appendices at the end)

And, I intend to release a preprint that has the main paper and appendicies in one PDF.

So, what I would like to do is to have one numbered reference list (generated by bibtex) that is shared across both PDFs. And, for the use-case of submitting to the conference that wants two PDFs, I want to do something like this:

\begin{document}
\section{Introduction}
...
\section{Conclusion}

\bibliography{bibliography}
\bibliographystyle{ieee}

% ---- begin supplementary material ----

\section*{Appendix A}

% print the bibliography again
\bibliography{bibliography}
\bibliographystyle{ieee}

\end{document}


When I do the above, it complains that Label '2018_authorname' multiply defined. (2018_authorname is the name of an item in the bibliography file that I supply to bibtex.)

So, one solution I am trying to figure out is: can I somehow print the bibliography as a string to a variable (like you would in a normal computer program), and then print that string in two different places in the document?

Or, are there other ways that people have dealt with this?

• Replace the second invocation of \bibliography{bibliography} by \InputIfFileExists{bibliography.bbl}{}{}. – Henri Menke May 26 '20 at 23:19

I learned that it is straightforward to print the bibliography multiple times if I use biblatex instead of bibtex. That's because biblatex provides the \printbibliography command, which can be called multiple times.

Here's what I came up with:

\usepackage[backend=biber, style=ieee]{biblatex}

\begin{document}
\section{Introduction}
...
\section{Conclusion}

\printbibliography

% ---- begin supplementary material ----

\section*{Appendix A}

% print the bibliography again
\printbibliography

\end{document}


I added the ieee.bbx and ieee.cbx files from this package to my working directory, and that enabled biblatex to use style=ieee in the above.

To answer the original question using \bibliography, here is how you make a duplicate

% print the bibliography again
\begin{@fileswfalse}
\bibliography{bib}
\end{@fileswfalse}


If you make a TOC entry, put it before the \begin.