biblatex's \footfullcite typesets citation twice in beamer

Question

Consider main.bib:

@techreport{2012FracfocusChemical,
  author = {FracFocus,},
  howpublished = {\url{http://fracfocus.org/water-protection/drilling-usage}},
  institution = {The Ground Water Protection Council and Interstate Oil and Gas
  Compact Commission},
  month = {feb},
  title = {{Chemical Use In Hydraulic Fracturing}},
  year = {2012}
}

Consider mwe.tex:

\documentclass {beamer}

\usepackage [backend=biber,style=authoryear] {biblatex}
  \addbibresource{main.bib}

\newcommand{\currentpart}{}
\let\oldpart = \part
\renewcommand{\part}[1]{%
  \oldpart{#1}
  \renewcommand{\currentpart}{#1}
}

\newcommand{\currentsection}{}
\let\oldsection = \section
\renewcommand{\section}[1]{%
  \oldsection{#1}
  \renewcommand{\currentsection}{#1}
}

\begin{document}

\begin{frame}
  \frametitle{\currentpart}
  \framesubtitle{\currentsection}
  \begin{block}{}
\begin{figure}
  \begin{minipage}{4.5in}
    \centering
    \fbox{%
%       \includegraphics[scale=0.2]{../Pictures/active_research}
    }
    \caption{Conceptualization of the process of Carbon Capture, Utilization,
    and Sequestration highlighting active research
    areas\footfullcite{2012FracfocusChemical}.}
    \label{fig:active_research}
  \end{minipage}
\end{figure}
  \end{block}
\end{frame}

\end{document}

Why does the \footfullcite instruction typesets double citation? I.e., this occurs:

Also:

C:\Users\ejspeiro>biber --version
biber version: 1.8

C:\Users\ejspeiro>pdflatex --version
MiKTeX-pdfTeX 2.9.4902 (1.40.14) (MiKTeX 2.9)
Copyright (C) 1982 D. E. Knuth, (C) 1996-2012 Han The Thanh
TeX is a trademark of the American Mathematical Society.

Answer 1

Do you really need footnotes in a presentation inside a caption?

The problem observed is a bad interaction with the moving argument from \caption You can prevent it by using \footnotemark and \footnotetext{\fullcite{<key>}}, but the marker will still need manual adjustment:

\documentclass {beamer}
\usepackage{filecontents}
\begin{filecontents*}{main.bib}
@techreport{2012FracfocusChemical,
  author = {FracFocus,},
  howpublished = {\url{http://fracfocus.org/water-protection/drilling-usage}},
  institution = {The Ground Water Protection Council and Interstate Oil and Gas
  Compact Commission},
  month = {feb},
  title = {{Chemical Use In Hydraulic Fracturing}},
  year = {2012}
}
\end{filecontents*}

\usepackage [backend=biber,style=authoryear] {biblatex}
  \addbibresource{main.bib}

\newcommand{\currentpart}{}
\let\oldpart = \part
\renewcommand{\part}[1]{%
  \oldpart{#1}
  \renewcommand{\currentpart}{#1}
}

\newcommand{\currentsection}{}
\let\oldsection = \section
\renewcommand{\section}[1]{%
  \oldsection{#1}
  \renewcommand{\currentsection}{#1}
}

\begin{document}

\begin{frame}
  \frametitle{\currentpart}
  \framesubtitle{\currentsection}
  \begin{block}{}
\begin{figure}
  \begin{minipage}{4.5in}
    \centering
    \fbox{%
%       \includegraphics[scale=0.2]{../Pictures/active_research}
    }
    \caption{Conceptualization of the process of Carbon Capture, Utilization,
    and Sequestration highlighting active research
    areas\footnotemark[1].}
    \label{fig:active_research}
  \end{minipage}
    \footnotetext[1]{\fullcite{2012FracfocusChemical}}
\end{figure}
  \end{block}
\end{frame}

\end{document}

In comments it's been discussed that the intent is to cite the source for the image; in this case, I'd suggest to get rid of footnotes and add the source directly under the image's caption, using something like the following:

\documentclass {beamer}
\usepackage{filecontents}
\begin{filecontents*}{main.bib}
@techreport{2012FracfocusChemical,
  author = {FracFocus,},
  howpublished = {\url{http://fracfocus.org/water-protection/drilling-usage}},
  institution = {The Ground Water Protection Council and Interstate Oil and Gas
  Compact Commission},
  month = {feb},
  title = {{Chemical Use In Hydraulic Fracturing}},
  year = {2012}
}
\end{filecontents*}

\usepackage [backend=biber,style=authoryear] {biblatex}
  \addbibresource{main.bib}

\newcommand{\currentpart}{}
\let\oldpart = \part
\renewcommand{\part}[1]{%
  \oldpart{#1}
  \renewcommand{\currentpart}{#1}
}

\newcommand{\currentsection}{}
\let\oldsection = \section
\renewcommand{\section}[1]{%
  \oldsection{#1}
  \renewcommand{\currentsection}{#1}
}

\begin{document}

\begin{frame}
  \frametitle{\currentpart}
  \framesubtitle{\currentsection}
  \begin{block}{}
\begin{figure}
  \begin{minipage}{4.5in}
    \centering
    \fbox{%
%       \includegraphics[scale=0.2]{../Pictures/active_research}
    }
    \caption{Conceptualization of the process of Carbon Capture, Utilization,
    and Sequestration highlighting active research
    areas.}
    {\raggedright\tiny Source: \fullcite{2012FracfocusChemical}\par}
    \label{fig:active_research}
  \end{minipage}
\end{figure}
  \end{block}
\end{frame}

\end{document}

Answer 2

Including the caption package (add \usepackage{caption} at the beginning of the file) removes the second citation.

\documentclass {beamer}

\usepackage[backend=biber,style=authoryear]{biblatex}
\addbibresource{biblatex-examples.bib}

\usepackage{caption}

\begin{document}

\begin{frame}
  \begin{block}{}
    \begin{figure}
      \begin{minipage}{4.5in}
        \centering
        \fbox{ }
        \caption{Conceptualization of the process of Carbon Capture, Utilization,
        and Sequestration highlighting active research
        areas\footfullcite{knuth:ct}.}
        \label{fig:active_research}
      \end{minipage}
    \end{figure}
  \end{block}
\end{frame}

\end{document}