Pages in beamer are incorectly numbered when using “show notes on second screen”

Question

I'm using beamer to create a presentation, and want to use the mode "show notes on second screen". Unfortunately, there seems to be a bug: when I turn it on, the page numbers are shifted one page up, so page 1 becomes 2, 2 becomes 3, and so on, with the last page number being repeated. With overlays, the numbers also shits one position, so the previous page of the overlay, and the last one has incorrect number.

I attach a minimum sample file: just check the PDF page numbers. By commenting the line \setbeameroption{show notes on second screen=left}, the numbers work fine; when adding it, the numbering fails.

\documentclass{beamer}

\usepackage[spanish]{babel}

\usepackage{pgfpages}

\setbeameroption{show notes on second screen=left}

\begin{document}

\begin{frame}
First frame (should be 1)
\end{frame}

\begin{frame}
Second frame (should be 2)
\end{frame}

\begin{frame}
Third frame (should be 3)\\

\pause
Also third frame (should also be 3)
\end{frame}

\begin{frame}
Fourth frame (should be 4)
\end{frame}

\end{document}