my %unique;
@unique{@values} = ();

for (@values) {
    next unless exists $unique{$_};
    print $_, $/;
    delete $unique{$_};
}

##</code><code>##

my %unique;
for (@values) {
    next if exists $unique{$_};
    print $_, $/;
    $unique{$_}++;
}