Beamer section page and show notes for every page

Question

I want to have a notepage for every single page, even if it will be empty. This I accomplished with the help of this answer https://tex.stackexchange.com/a/11724/36296

But now, I have the problem, that I also want to have a special page at the beginning of a new section. But when I try to add a \note{...} after a new section started, there is an additional empty notepage.

Edit:

The goal I am trying to achieve is that after the section page the note page with "notes to section page" follows immediately without an empty notepage first.

\documentclass{beamer}

\setbeameroption{show notes}

% notepage for every slide, even if empty
\makeatletter 
\def\beamer@framenotesbegin{%   
    \gdef\beamer@noteitems{}%   
    \gdef\beamer@notes{{}}%  
}
\makeatother

% section page
\AtBeginSection{%
    \begin{frame}
        \insertsection
    \end{frame}
}

\begin{document}

    \begin{frame}
        slide with note
        \note{testnote}
    \end{frame}

    \begin{frame}
        test with empty note
    \end{frame}

    \section{Section with note}
    \note{notes to section page}

\end{document}

Answer 1

You can use the beamer option show notes on second screen, which creates a double-width PDF document showing the actual frame on the left and the notes on the right. It ensures that each frame is followed by exactly one note page, so it doesn't need the manual solution described in Run macro on each frame in beamer. This approach relies on the package pgfpages, which has to be loaded manually before using the option:

\documentclass{beamer}

\usepackage{pgfpages}
\setbeameroption{show notes on second screen}

% section page
\AtBeginSection{%
    \begin{frame}
        \insertsection
    \end{frame}
}

\begin{document}

    \begin{frame}
        slide with note
        \note{testnote}
    \end{frame}

    \begin{frame}
        test with empty note
    \end{frame}

    \section{Section with note}
    \note{notes to section page}

\end{document}

Answer 2

diabonas answered exactly the question I had asked. But unfortunately his approach caused follow up problems when creating print versions with multiples frames per page (see follow up question)

A possibility to avoid these problems is to define an own command for the section pages

\documentclass{beamer}

\setbeameroption{show notes}

% notepage for every slide, even if empty
\makeatletter 
\def\beamer@framenotesbegin{%   
    \gdef\beamer@noteitems{}%   
    \gdef\beamer@notes{{}}%  
}
\makeatother

% section page
\newcommand{\mysection}[2]{%
        \section{#1}
    \begin{frame}
        \insertsection
        \note{#2}
    \end{frame}
}

\usepackage{pgfpages}
\pgfpagesuselayout{8 on 1}

\begin{document}

    \begin{frame}
        slide with note
        \note{testnote}
    \end{frame}

    \begin{frame}
        test with empty note
    \end{frame}

    \mysection{Section with note}{notes to section page}

    \mysection{Section without notes}

\end{document}