Replacing characters in file names is just plain wrong in Unix. A space is a space, and not something else. And something that isn't a space, just isn't.

#!/usr/bin/perl

use 5.010;
use strict;
use warnings;

my $dir = "/tmp/Foo";

mkdir $dir or die;
chdir $dir or die;

opendir my $dh, $dir or die;
my @files = readdir $dh;
closedir $dh;
say "Got ", scalar @files, " files";

foreach my $char ("\x{20}", "\x{A0}") {
    my $file = "foo{$char}bar";
    open my $fh, ">", $file or die;
}

opendir $dh, $dir or die;
@files = readdir $dh;
closedir $dh;
say "Got ", scalar @files, " files";

__END__
Got 2 files
Got 4 files
[download]

See, two different files - one with a space, the other with a non-breaking space. No automatic conversion between them.