\newcommand{\DefineTracker}[3]{%
\expandafter\newcommand\csname trk-\detokenize{#1}-\detokenize{#2}\endcsname{#3}%
}%
\newcommand{\Tracker}[2]{\csname trk-\detokenize{#1}-\detokenize{#2}\endcsname}%
\makeatletter%
\newcommand{\replunderscores}[1]{\expandafter\@repl@underscores#1_\relax}
\def\@repl@underscores#1_#2\relax{%
    \ifx \relax #2\relax
        #1%
    \else
        #1%
        \textunderscore
        \@repl@underscores#2\relax
    \fi
}
\makeatother%