#!/usr/bin/perl

use strict;
use warnings;

my %h1 = (
 one => 1,
 two => 2,
);

my %h2 = (
 three => 3,
 four => 4,
);

my_sub(\%h1, \%h2);

sub my_sub {
my ($ref1, $ref2) = @_;
my %h1 = %{$ref1};
my %h2 = %{$ref2};

# Or "my %h1 = %{(shift)};" will work too, but I don't really like it.

 print "$_ $h1{$_}\n" for keys %h1;
 print "$_ $h2{$_}\n" for keys %h2;
}