在 beamer 中使用 natbib、citep 和超链接时，多重参考引用无法与 bibtex 配合使用

Question

我使用 Beamer 用 .bib 文件写了一些教学笔记。根据一些线索 约瑟夫赖特 和用户36296，我在我的小例子上做了一些测试如下：

    \documentclass{beamer}

    %\usepackage[comma,numbers,sort&compress]{natbib}
    \usepackage[authoryear,round]{natbib}
    %\bibliographystyle{plain}

    \hypersetup{
        colorlinks,
        citecolor=green,
        linkcolor=red,
        backref=true
    }

    \let\oldbibitem=\bibitem
    \renewcommand{\bibitem}[2][]{\label{#2}\oldbibitem[#1]{#2}}
    \let\oldcite=\cite
    \renewcommand\cite[1]{\hyperlink{#1}{\oldcite{#1}}}
    \let\oldcitep=\citep
    \renewcommand\citep[1]{\hyperlink{#1}{\oldcitep{#1}}}
    \let\oldciteauthor=\citeauthor
    \renewcommand\citeauthor[1]{\hyperlink{#1}{\oldciteauthor{#1}}} 
    \newcommand{\newblock}{}

    \begin{document}

    \title{Multiple reference citation: natbib + citep + hyperlink}
    \frame{ \titlepage }

    \begin{frame}{only}
    \only<1>{\begin{block}{block 1}
    \citep{hastie2009elements}
    \end{block}}
    \only<2>{\begin{block}{block 2}
    \citep{hastie2009elements,james2013introduction}
    \end{block}}
    \only<3>{\begin{block}{block 3}
    \citep{hastie2009elements},\citep{james2013introduction}
    \end{block}}
    \end{frame}


    \begin{frame}%[allowframebreaks]
    %\tiny
    \frametitle{References}
    \bibliographystyle{unsrtnat}
    \bibliography{test}
    \end{frame}

    \end{document}

该test.bib文件包含两个引用

    @book{james2013introduction,
    title={An introduction to statistical learning: with applications in R},
    author={James, Gareth and Witten, Daniela and Hastie, Trevor and Tibshirani, Robert},
    year={2013},
    publisher={Springer},
    address={New York}
    }
    @Book{hastie2009elements,
    Title       = {The elements of statistical learning: Data mining, inference, and prediction},
    Author      = {Hastie, Trevor and Tibshirani, Robert and Friedman, Jerome},
    edition   = {2},
    Publisher   = {Springer},
    address      ={New York},
    Year        = {2009}
    }

它与指向单个引用的参考文献页面的正确超链接配合得很好（即\citep{hastie2009element}​​或\citep{james2013introduction}）。但是，单击包含多个参考文献的 PDF\citep{hastie2009elements,james2013introduction} 总是会转到标题页！有什么帮助吗？