\documentclass{article}
\usepackage{tikz}
\usepackage{fp}
\usepackage{overpic}
\usepackage[francais,bloc]{automultiplechoice}

\begin{document}
\makeatletter
\pgfmathsetseed{123321}
\def\prunelist#1{%
\expandafter\edef\csname pgfmath@randomlist@#1\endcsname
        {\the\numexpr\csname pgfmath@randomlist@#1\endcsname-1\relax}
\count@\pgfmath@randomtemp 
\loop
\expandafter\let
\csname pgfmath@randomlist@#1@\the\count@\expandafter\endcsname
\csname pgfmath@randomlist@#1@\the\numexpr\count@+1\relax\endcsname
\ifnum\count@<\csname pgfmath@randomlist@#1\endcsname\relax
\advance\count@\@ne
\repeat
}
\makeatother

\pgfmathdeclarerandomlist{mylist}{ {10} {27} {32} {43} {51} {65} {78}}
\exemplaire{2}{
blabla\\
\pgfmathrandomitem\z{mylist}\prunelist{mylist}
\FPeval\varA{\z}
\pgfmathrandomitem\z{mylist}\prunelist{mylist}
\FPeval\varB{\z}
\pgfmathrandomitem\z{mylist}\prunelist{mylist}
\FPeval\varC{\z}

\begin{overpic}[width=0.45\textwidth]{image.PNG}
\put (1,64) {\varA}
\put (57,28.5) {\varB}
\put (57,24) {\varC}
\end{overpic}

\varA

\varB

\varC

}
\end{document}
