my $key;

  ...

<select name="$key" size="15" multiple="multiple">

##</code><code>##

my $name = "multi";  # Renamed from $key to be less confusing

# Sorry, I don't want to show my /etc/password :)
my %user = (
    'fred'     => 101,
    'barney'   => 102,
    'wilma'    => 103,
    'betty'    => 104,
    'pebbles'  => 105,
    'bambam'   => 106,
);

...
<select name="$name" size="15" multiple="multiple">

foreach my $key(sort keys %user) {
    my $val = $user{$key};
    if ($val > 100) {
        print qq{<option value="$key">$key ($val)</option><br />};
    }
}

##</code><code>##

#!/usr/bin/perl

use strict;
use warnings;
use CGI qw/:standard/;
use CGI::Carp qw/fatalsToBrowser/;
use Data::Dumper;

my @users = param('multi');
die sprintf "Users selected:  %s\n", Dumper(\@users);



##</code><code>##

*** bambam (106) ****
    barney (102)
    betty (104)
    fred (101)
*** pebbles (105) ***
    wilma (103)

##</code><code>##

Software error:

Users selected:  $VAR1 = [
          'betty',
          'wilma'
        ];