diff -Naur latex2html-2024.orig/docs/l2hfiles.dat latex2html-2024/docs/l2hfiles.dat
--- latex2html-2024.orig/docs/l2hfiles.dat	2024-01-01 22:13:03.000000000 +0700
+++ latex2html-2024/docs/l2hfiles.dat	2024-05-28 12:33:22.273968338 +0700
@@ -190,6 +190,7 @@
 \item[\gn{\$TOP\_NAVIGATION}] when set, a navigation panel is placed at the top of every \texttt{HTML} page, unless overridden by \fn{\$NO\_NAVIGATION} being set also
 \item[\gn{\$TRANSPARENT\_FIGURES}] when set, this specifies that the background of generated images should be made transparent
 \item[\gn{\$TRANSPARENT\_IMAGES}] when set, this \emph{prevents} the background of images from being made transparent (no longer used)
+\item[\gn{\$UNICASE\_TITLES}] when set, duplication of generated filenames for \texttt{HTML} pages is checked in case insensitive manner
 \item[\gn{\$UNSEGMENT}] when set, \latextohtml{} translates a segmented document as a whole rather than a single segment; use this for testing your segmented document
 \item[\gn{\$UP}] when navigation panels are created, this holds a hyperlink to the parent \texttt{HTML} page
 \item[\gn{\$UP\_TITLE}] when navigation panels are created, this holds a title of the parent \texttt{HTML} page
diff -Naur latex2html-2024.orig/docs/userman.tex latex2html-2024/docs/userman.tex
--- latex2html-2024.orig/docs/userman.tex	2024-01-01 22:13:03.000000000 +0700
+++ latex2html-2024/docs/userman.tex	2024-05-28 12:34:01.584377906 +0700
@@ -237,11 +237,18 @@
 for that page, separated by the `\texttt{\_}' character.\html{\\}
 Commas and common short words (\texttt{a an to by of and for the})
 are omitted from both title and word-count.
+When duplication of constructed filenames is detected (see also the
+\htmlref{-unicase\_titles}{cs_unicasetitles} option),
+an incremented number starting from 2 is appended to each duplicated filename.
 
-\smallskip\noindent
-\textbf{Warning:} Use this switch with great caution.
-Currently there are no checks for uniqueness of names or overall length. 
-Very long names can easily result from using this feature.%
+\index{filenames!long names}
+\index{filenames!case insensitive}
+
+\item [ -unicase\_titles\label{cs_unicasetitles}]
+\sameas{\fn{\$UNICASE\_TITLES}\texttt{ = 1;}}\\
+If set, and the \htmlref{-long\_titles}{cs_longtitles} option is used,
+duplication of generated filenames is checked in case insensitive manner.
+Useful under case insensitive filesystems such as NTFS or FAT.
 
 \index{filenames!customised}%
 \index{filenames!custom title hook@\texttt{custom\_title\_hook}}
diff -Naur latex2html-2024.orig/l2hconf.pin latex2html-2024/l2hconf.pin
--- latex2html-2024.orig/l2hconf.pin	2024-01-01 22:13:03.000000000 +0700
+++ latex2html-2024/l2hconf.pin	2024-05-28 12:34:29.734671249 +0700
@@ -997,6 +997,15 @@
 #	or when you specify the language through the babel package.
 
 
+# When the -long_titles option is used, duplication of generated filenames
+# which differ only in letter case is checked as follows:
+# $UNICASE_TITLES = 0: such filenames are treated as unique
+#		       (for case sensitive filesystems typical under Unix)
+# $UNICASE_TITLES = 1: such filenames are treated as duplicated
+#		       (for case insensitive filesystems such as NTFS or FAT)
+$UNICASE_TITLES = 0;
+
+
 ### Verbosity #################################################################
 #
 # -verbosity
diff -Naur latex2html-2024.orig/latex2html.1 latex2html-2024/latex2html.1
--- latex2html-2024.orig/latex2html.1	2024-01-01 22:13:03.000000000 +0700
+++ latex2html-2024/latex2html.1	2024-05-28 12:35:00.024986931 +0700
@@ -76,9 +76,19 @@
 section heading for that page, separated by the `_' character.
 Commas and common short words (a an to by of and for the) are omitted
 from both title and word-count.
-Warning: Use this switch with great caution. Currently there are no
-checks for uniqueness of names or overall length. Very long names can
-easily result from using this feature.
+When duplication of constructed filenames is detected (see also the
+.B -unicase_titles
+option), an incremented number starting from 2
+is appended to each duplicated filename.
+.TP
+.B -unicase_titles
+Same as setting:
+.I $UNICASE_TITLES = 1;
+If set, and the
+.B -long_titles
+option is used, duplication of generated filenames
+is checked in case insensitive manner.
+Useful under case insensitive filesystems such as NTFS or FAT.
 .TP
 .B -custom_titles
 Same as setting:
diff -Naur latex2html-2024.orig/latex2html.pin latex2html-2024/latex2html.pin
--- latex2html-2024.orig/latex2html.pin	2024-01-01 22:13:03.000000000 +0700
+++ latex2html-2024/latex2html.pin	2024-05-28 12:35:26.205259816 +0700
@@ -274,6 +274,7 @@
         'prefix=s',             \$PREFIX,
         'auto_prefix!',         \$AUTO_PREFIX,
         'long_titles=i',        \$LONG_TITLES,
+        'unicase_titles!',      \$UNICASE_TITLES,
         'custom_titles!',       \$CUSTOM_TITLES,
         'title|t=s',            \$TITLE,
         'rooted!',              \$ROOTED,
@@ -695,6 +696,26 @@
     print "\n *** initialise *** " if ($VERBOSITY > 1);
     &initialise;		# Initialise some global variables
 
+    # Early reservation of filename for auto-linked index.html to avoid
+    # eventual duplication if some later generated page would get name 'Index'.
+    # This code to generate "$to" adopted from the do-block with the clause
+    # "L2hos->Link($from,$to);" about 200 lines later.
+    do {
+        local($EXTN) = $EXTN;
+	$EXTN =~ s/_\w+(\.html?)/$1/ if ($frame_main_name);
+	local($from,$to) = (eval($LINKPOINT),eval($LINKNAME));
+	$from = &make_long_title($LONG_LINKPOINT) . $EXTN
+	    if ($LONG_TITLES && $LONG_LINKPOINT);
+	if (length($from) && length($to) && ($from ne $to)) {
+	    $to =~ s/$frame_main_name(\.html?)/$1/ if ($frame_main_name);
+	    if ($UNICASE_TITLES) {
+	        $nodenames{"\L$to"} = 1;
+	    } else {
+	        $nodenames{$to} = 1;
+	    }
+	}
+    } unless ($NO_AUTO_LINK || !($LINKPOINT) || !($LINKNAME));
+
     print "\n *** check modes *** " if ($VERBOSITY > 1);
     &ascii_mode if $ASCII_MODE;	# Must come after initialization
     &titles_language($TITLES_LANGUAGE);
@@ -9876,7 +9897,7 @@
 sub make_name {
     local($sec_name, $packed_curr_sec_id) = @_;
     local($title,$making_name,$saved) = ('',1,'');
-    local($filename) = '';
+    local($filename,$dupname) = ('','');
     if ($LONG_TITLES) {
 	$saved = $_;
 	&process_command($sections_rx, $_) if /^$sections_rx/;
@@ -9896,12 +9917,14 @@
     	++$OUT_NODE;
 	$filename = join("", ${PREFIX}, $title, $EXTN);
 	# Avoid duplication of filenames
-	unless ($nodenames{$filename}) {
-	    $nodenames{$filename} = 1;
+	$dupname = $filename;
+	$dupname = "\L$filename" if $UNICASE_TITLES;
+	unless ($nodenames{$dupname}) {
+	    $nodenames{$dupname} = 1;
 	} else {
 	    # Duplication detected: add version number to generated filename
 	    $filename =
-		join("", ${PREFIX}, $title, ++$nodenames{$filename}, $EXTN);
+		join("", ${PREFIX}, $title, ++$nodenames{$dupname}, $EXTN);
 	}
 	$filename;
     } else {
@@ -17650,6 +17673,7 @@
 S<[ B<-prefix> I<output_filename_prefix> ]>
 S<[ B<->(B<no>)B<auto_prefix> ]>
 S<[ B<-long_titles> I<num> ]>
+S<[ B<->(B<no>)B<unicase_titles> ]>
 S<[ B<->(B<no>)B<custom_titles> ]>
 S<[ B<-title>|B<-t> I<top_page_title> ]>
 S<[ B<->(B<no>)B<rooted> ]>
@@ -17869,7 +17893,15 @@
 
 The filenames for each HTML page are constructed from the first I<num>
 words of the section heading for that page, separated by the `_'
-character.
+character. When duplication of constructed filenames is detected
+(see also the B<-unicase_titles> option), an incremented number
+(starting from 2) is appended to each duplicated filename.
+
+=item B<->(B<no>)B<unicase_titles>
+
+If set, and the B<-long_titles> option is used, duplication of
+generated filenames is checked in case insensitive manner.
+Useful under case insensitive filesystems such as NTFS or FAT.
 
 =item B<->(B<no>)B<custom_titles>