How can one undo many hard links?

"Since you've converted them into hard links, you might be in luck and they might still show up as duplicates using something like DoubleKiller.
Either way, I doubt there's a utility for this exact task.

If all else fails I recommend a re-install..."

"Try Hard Link Magic, it might help.

Also Microsoft's Junction has the ability to recursively traverse directories and list/delete junction-points.

Just be careful to create a system restore point before you do these manipulations."

"I have written a Perl script that identifies all regular files that are hard links to the same data. The script works fine on UNIX and Cygwin. I haven’t tested it with Strawberry Perl or any other Windows port of Perl, but I thought I’d share it anyhow. On Windows (Cygwin) I would open a terminal and do ./list-dup-hard-links /cygdrive/c/.

#!/usr/bin/perl
#
# NAME
#
# list-dup-hard-links - list regular file names pointing to the same inode
#
# SYNOPSIS
#
# list-dup-hard-links DIRECTORY
#
# DESCRIPTION
#
# For each inode that is referred to by more than one regular file, print
# the inode number and the list of corresponding files.
#
# AUTHOR
#
# Peter John Acklam <pjacklam@online.no>

use strict; # restrict unsafe constructs
use warnings; # control optional warnings
use File::Find; # traverse a file tree

if (@ARGV != 1) {
die ""Usage: $0 DIRECTORY\n"";
}

my $start_dir = shift; # starting directory
my $start_dev = (stat $start_dir)[0]; # device number of where we start
my %inum2files; # map each inode number to file(s)

sub wanted {
return if -l; # skip symlinks
my @fileinfo = stat(); # get file info

if (-d _) { # if a directory
my $this_dev = $fileinfo[0]; # get device number
if ($this_dev != $start_dev) { # if we crossed a device boundary
$File::Find::prune = 1; # mark directory for pruning
return; # and return
}
}

return unless -f _; # continue only if a regular file

my $inum = $fileinfo[1]; # get inode number
push @{ $inum2files{$inum} }, # append this file to the list of
$File::Find::name; # all files with this inode number
}

find(\&wanted, $start_dir); # traverse the file tree

while (my ($inum, $files) = each %inum2files) {
next if @$files < 2; # skip non-duplicates

print ""\nInode number: $inum\n\n"" # print header
or die ""$0: print failed: $!\n"";

for my $file (@$files) {
print "" $file\n"" # print file name
or die ""$0: print failed: $!\n"";
}
}"

In Unix, hard links to one file links same "inode number". "stat" function returns file properties like size, mode, alter date, modification date, inode number, ..., but return inode number "0" for any file in Windows. Use perl Win32::IdentifyFile (CPAN) to get a file disk "localization". Hard links "links" to same disk "localization".