use strict ;
use warnings;
use threads;
use threads::shared;
use Data::Dumper;
my %HoH           :shared;
my %hash          :shared;     

$hash{pre_key} = "Before";
$HoH{hash}=\%hash;
$hash{post_key} = "After";

if (\%hash eq $HoH{hash}) {
   print "OK\n";
} else {
   print "Copied, I suspect\n";
}

print Data::Dumper->Dump ([\%hash], ["hash"]);
print Data::Dumper->Dump ([$HoH{hash}], ["HoH"]);

print "But looks like they still stay in sych\n