# Beamer \only or \onslide in presence of notes pages

When I use \only<#> in the \note{} section of my beamer slides, I'm getting odd behavior where an extra slide gets generated at the end of each series of slides. For example the following document:

\documentclass[xcolor={dvipsnames,svgnames}]{beamer}
\usetheme{CambridgeUS}
\usecolortheme{spruce}
\usefonttheme{serif}

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

\begin{document}
\begin{frame}
\begin{itemize}
\item<1> Foo
\item<2> Bar
\end{itemize}
\note{\only<1>{Say Foo}\only<2>{Say Bar}}
\end{frame}
\end{document}


This results in three frames being generated, when I expected there to be only two because I only referenced slide numbers 1 and 2 in both the itemize and the \note{}. What gives?

I can achieve the desired effect by making multiple notes, each in their own \only<>{}:
  \only<1>{\note{Say Foo}}

But the question still stands, as to why an only{} inside a \note{} acts so weird.