#! /usr/bin/perl
use strict;
use warnings;
use Storable qw( dclone );

my $hRef = {
  foo => {
    bar => 123,
  }
};

my $copy = dclone( $hRef );

$hRef->{foo}->{bar} = 456;


require Data::Dumper;
print Data::Dumper->Dump(
  [ $hRef, $copy ],
  [ wq( *hRef *copy ],
);