my ($title, $artist, $mp3_file);

foreach my $file (@file_names) {
    $mp3_file = new MP3::ID3v1Tag("$file");
    $title = $mp3_file->get_title();
    $artist = $mp3_file ->get_artist();

    print "$title - artist\n";
}

##</code><code>##

my ($title, $artist, $mp3_file);

foreach my $file (@file_names) {
    print "now working with file '$file'\n";
    # remove mp3_file from the my declaration outside the loop
    my $mp3_file = new MP3::ID3v1Tag("$file");
    die "Can't create id tag : $!" unless $mp3_file;
    $title = $mp3_file->get_title();
    $artist = $mp3_file ->get_artist();

    print "$title - artist\n";
}