Springer LNCS Template: Same footnote for two authors

In the lack of a MWE this is a quick and dirty solution using the article class …

\documentclass{article}

\newcommand{\repeatthanks}{\textsuperscript{\thefootnote}}

\begin{document}
\title{Title}
\author{Author1\thanks{Text}, Author2\repeatthanks}
\maketitle
\end{document}

It will only work if there’s no other \thanks in between.

The llncs class treats \thanks differently from the standard classes. But some tricks make the thing possible.

\documentclass[runningheads]{llncs}

\usepackage{etoolbox}

\usepackage{kantlipsum} % just for the example

\newcommand{\repthanks}[1]{\textsuperscript{\ref{#1}}}
\makeatletter
\patchcmd{\maketitle}
  {\def\thanks}
  {\let\repthanks\repthanksunskip\def\thanks}
  {}{}
\patchcmd{\@maketitle}
  {\def\thanks}
  {\let\repthanks\@gobble\def\thanks}
  {}{}
\newcommand\repthanksunskip[1]{\unskip{}}
\makeatother


\begin{document}

\title{LaTeX Template for Your LNCS Paper}

\author{Author 1\thanks{Supervised by Author 9\protect\label{X}}, Author 2\repthanks{X}}

\institute{Lab, University, Address}
\maketitle

\begin{abstract}
Abstract is here.
\end{abstract}

\section{Introduction}\label{sec:Introduction}

The rest goes here.

\kant

\end{document}

You need to do \protect\label{<whatever>} in the \thanks command you want to repeat and \repthanks{<whatever>} for repeating the footnote marker.

A similar adjustment could be made, if necessary, also for the \institute part.