# How to avoid extra slide when using overlays in notes?

I want to sync presentation and node contents using overlays. I tried to read the Beamer User Guide, but it's too many details and information.

This is a MWE:

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

\begin{document}

\begin{frame} %<-3>
Line 1

\onslide<2->{Line 2}

\onslide<3->{Line 3}

Line 4

\note{
Talk about lines 1 and 4

}
\end{frame}

\end{document}


In this example, I would expect three slides, but I got four. The problem is that a replica of the last slide is also created.

The same issue happens when using \only, \visible, \uncover etc. I tried other options (<.->, <.>, <+->...) without success.

I don't want to use the itemize environment because the frame contents will not be a bullet list. Instead, it will include graphics, images and charts, as well as pseudocode. The MWE was designed only to reproduce the problem.

So far, I managed to cut off the superfluous slide by adding <-3> to the frame overlay specification (commented out in the MWE).

Well, If I could understand why the extra slide is created, I could use a more appropriate solution. :-)

I did not yet investigate why the 4th page is there (really strange!), but here one workaround until the problem is identified:

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

\begin{document}

\begin{frame} %<-3>
Line 1

\onslide<2->{Line 2}

\onslide<3->{Line 3}

Line 4

\note{Talk about lines 1 and 4

}