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)
[download]

Produces:

{
  key1 => [["1.1.1", "1.1.2", "1.1.3"], ["2.1.1", "2.1.2", "2.1.3"]],
  key2 => [["1.2.1", "1.2.2", "1.2.3"], ["2.2.1", "2.2.2", "2.2.3"]],
}
[download]

Thank you philiprbrenan.

But for %h2, the keys are supposed to be values in %h1

i.e the keys for %h2 are:

1.1.1

1.1.2

1.1.3

1.2.1

1.2.2

1.2.3

For each of the key, e.g 1.1.1, it would have different values in %h2: e.g.:

1.1.1=> qw(3.3.1,3.3.2,3.3.3)

1.1.2=> qw(4.4.1, 4.4.2, 4.4.3)

1.1.3=> qw(5.5.1, 5.5.2, 5.5.3)

1.2.1=> qw(6.6.1, 6.6.2, 6.6.3)

1.2.2=> qw(7.7.1, 7.7.2, 7.7.3)

1.2.3=> qw(8.8.1, 8.8.2, 8.8.3)

so the end results i desire would be:

key1=>qw(3.3.1,3.3.2,3.3.3, 4.4.1, 4.4.2, 4.4.3, 5.5.1, 5.5.2, 5.5.3)

key2=>qw(6.6.1, 6.6.2, 6.6.3,7.7.1, 7.7.2, 7.7.3,8.8.1, 8.8.2, 8.8.3)

That is that the keys from %h1 will have values from %h2.