use strict;
use warnings;
use Data::Dump qw/pp dd/;


my %h1 = (
    'Tim' => {
        'abc' => 7,
        'def' => 7,
        'ghi' => 0
    },
    'Adam' => {
        'abc' => 0,
        'def' => 0,
        'ghi' => 0
    },
    'keas' => {
        'abc' => 0,
        'def' => 0,
        'ghi' => 0
    }
);

my %h2 = (
    'Dav' => {
        'jkl' => 12,
        'mno' => 34,
        'pqr' => 45
    },
    'Adam' => {
        'jkl' => 7,
        'mno' => 0,
        'pqr' => 7
    }
);

my %joined_1st = (%h1,%h2);

#pp \%joined_1st;

my %joined_2nd =
    map { $_ => { %{ $h1{$_} // {} }, %{ $h2{$_} // {} } } }
    keys %joined_1st;

pp \%joined_2nd;

##</code><code>##

{
  Adam => { abc => 0, def => 0, ghi => 0, jkl => 7, mno => 0, pqr => 7 },
  Dav  => { jkl => 12, mno => 34, pqr => 45 },
  keas => { abc => 0, def => 0, ghi => 0 },
  Tim  => { abc => 7, def => 7, ghi => 0 },
}