\begin{frame}{Plan}
 \begin{columns}[t]
  \begin{column}{5cm}
   \tableofcontents[sections={1-6},currentsection, hideothersubsections]
  \end{column}
  \begin{column}{5cm}
   \tableofcontents[sections={7-12},currentsection,hideothersubsections]
  \end{column}
 \end{columns}
\end{frame}