ручной обходной путь:
\documentclass{beamer}
\usepackage[style=authoryear]{biblatex}
\usepackage{filecontents}
\begin{filecontents*}{\jobname.bib}
@book{knuth,
author = {Knuth, Donald E.},
title = {The {\TeX} book},
date = 1984,
maintitle = {Computers \& Typesetting},
volume = {A},
publisher = {Addison-Wesley},
location = {Reading, Mass.},
langid = {english},
langidopts = {variant=american},
sortyear = {1984-1},
sorttitle = {Computers & Typesetting A},
indexsorttitle= {The TeXbook},
indextitle = {\protect\TeX book, The},
shorttitle = {\TeX book}
}
\end{filecontents*}
\addbibresource{\jobname.bib}
\begin{document}
\begin{frame}
test\footcite{knuth}
test\footnotemark[1]
\end{frame}
\end{document}