use feature ":5.14";
use warnings FATAL => qw(all);
use strict;
use Data::Dump qw(dump pp);

my %h1 = (key1=>[qw(1.1.1 1.1.2 1.1.3)], key2=>[qw(1.2.1 1.2.2 1.2.3)]);
my %h2 = (key1=>[qw(2.1.1 2.1.2 2.1.3)], key2=>[qw(2.2.1 2.2.2 2.2.3)]);

my %c; 
for my $h(\%h1, \%h2)
 {push @{$c{$_}}, $h->{$_} for keys %$h;
 }

pp(\%c)