my %a = (
  k1 => 1,
  k2 => {
    kk3 => 3
  },
);

my %b = (
  k1 => 5,
  k2 => {
    kk4 => 4
  },
);
my %c = (%a,%b);

##</code><code>##

%c = (
   'k1' => 5
   'k2' => {
       'kk4' => 4
   },
);