I could install a pre compiled ActiveState distribution of the module (on ActivePerl) just for the sake of testing (I normally work on Strawberryperl): However this simple operation fails

use Win32::Unicode;
use Win32::Unicode::Dir;
use Win32::Unicode::Error;

my $from="FROM";
my $to="TO";

cptreeW $from, $to or die $!;
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No matter if the directory "TO" already exists or not: Undefined subroutine &Errno::ERROR_FILE_EXISTS called at C:/Perl/site/lib/Win32/Unicode/Error.pm line 31.