use warnings;
use strict;
use Data::Dump 'dd';
use Storable 'dclone';

my $hr =                        { foo => { bar => "quz" } };

my $deep = dclone($hr);
$deep->{foo}{bar} = 'baz';
$deep->{x} = 'y';
dd $deep;                     # { foo => { bar => "baz" }, x => "y" }
dd $hr;                       # { foo => { bar => "quz" } } unchanged

my $shallow = { %{ $hr } };
$shallow->{foo}{bar} = 'baz';
$shallow->{x} = 'y';
dd $shallow;                  # { foo => { bar => "baz" }, x => "y" }
dd $hr;                       # { foo => { bar => "baz" } }
                              #  original changed  ^^^