Select Code to Download

my %seen = (); # use hash for counting elements
my @doubles = grep {
...
  print "$element\n";
} # foreach @doubles
undef %seen;

my %seen = ();
$seen{$_}++ for @array1;
for my $value ( keys %seen ) {
  print "$value\n" if $seen{$value} > 1;
} # for %seen