use Data::Dumper;

use strict;
use warnings;

foo(
      animal => 'monkey',
      fish   => 'tuna',
      insect => 'ant',
      insect => 'spider'
);

sub foo {
	my %params = @_;
	print Dumper(\%params);
} 

##</code><code>##

$VAR1 = {
          'insect' => 'spider',
          'animal' => 'monkey',
          'fish' => 'tuna'
        };