TeX4ht generates a double footnotes when a footnote is defined inside of a csquotes
\blockquote
.
Here is a LaTeX reproducible example:
\documentclass[a4paper]{report}
\usepackage{csquotes}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\begin{document}
\section{About Color Science}
The International Commission on Illumination (CIE) defines perceived color as
the~\blockquote{characteristic of visual perception that can be
described by attributes of hue~\footnote{See sub-section~\ref{subsec:terminology}
for the definitions of hue, brightness, lightness, colorfulness, saturation and
chroma.}, brightness (or lightness) and colourfulness (or saturation or
chroma).}
\end{document}
My TeX4ht stripped config:
\Preamble{3,charset=utf-8,fn-in,html5,sec-filename,sections+,xhtml}
\EndPreamble
And the relevant HTML output:
<div class="footnotes"><!--l. 16--><p class="noindent"><span class="footnote-mark"><a href="#fn1x0-bk" id="fn1x0"><sup class="textsuperscript"><span class="ec-lmr-9">1</span></sup></a></span>See sub-section ?? for the definitions of hue, brightness, lightness, colorfulness, saturation and
chroma.</p><!--l. 16--><p class="indent"> <span class="footnote-mark"><a href="#fn1x0-bk"><sup class="textsuperscript"><span class="ec-lmr-9">1</span></sup></a></span>See sub-section ?? for the definitions of hue, brightness, lightness, colorfulness, saturation
and chroma.</p> </div>