Multiple versions include of a chapter

Question

I would like to include a chapter two times, a short version in the main part and a long version in the appendix. Everything works fine except the labels and references. Is there a way to redefine labels in a local context? I could us a \IFDEFINE statement around every label or ref but that is not very convenient.

Any suggestions welcome, Thx!!

==================== main.tex =================
\documentclass[12pt,a4paper]{book}
\usepackage[utf8]{inputenc}
\usepackage[german]{babel}
\begin{document}
\include{kapitel}
\begin{appendix}
\newcommand*{\LONGVERSION}{}
\include{kapitel}
\end{appendix}
\end{document}

==================== kapitel.tex =================
\chapter{This is a chapter}\label{chap:mychapter}
This is a test with a reference to my chapter \ref{chap:mychapter}
\ifdefined\LONGVERSION
\section{Variant LONG}
This is a long version of the chapter, which contains a lot of 
additional information. This shall be placed in the appendix.
\else
\section{Variant SHORT}
This is the short version.
\fi

Answer 1

One possibility is to use a \labelprefix which is changed according to the toggle switch longversion (I used etoolbox macros for this) and a predefined \shortlabelprefix and \longlabelprefix.

However, this does not work, if the short version of the chapter is input via \include twice, since each input overwrites the old label values.

main.tex

\documentclass[12pt,a4paper]{book}
\usepackage{etoolbox}
\usepackage[utf8]{inputenc}
\usepackage[ngerman]{babel}
\newcommand\shortlabelprefix{short}%
\newcommand\longlabelprefix{long}%
\newcommand\labelprefix{\shortlabelprefix}%


\newtoggle{longversion}
\togglefalse{longversion}

\begin{document}
\input{kapitel}


\begin{appendix}
\renewcommand{\labelprefix}{\longlabelprefix}
\toggletrue{longversion}
\include{kapitel}
\end{appendix}

\end{document}

kapitel.tex

\chapter{This is a chapter}\label{\labelprefix::chap:mychapter}
This is a test with a reference to my chapter \ref{\labelprefix::chap:mychapter}
\iftoggle{longversion}{%
\section{Variant LONG}
This is a long version of the chapter, which contains a lot of 
additional information. This shall be placed in the appendix.
}{%
\section{Variant SHORT}
This is the short version.
}

short variant

long variant