use strict;
use warnings;

my %hBase = ( 'a;a' => 1, 'b;b' => 2, 'c;c' => 3 );
my %hPost = ( 'a;a' => 1, 'b;b' => 3, 'd;d' => 4 );

my %allKeys = map {$_=>1} keys %hBase, keys %hPost;

for my $key (keys %allKeys) {
  if( exists $hBase{$key} and exists $hPost{$key} ) {
    if( $hBase{$key} eq $hPost{$key} ) {
      print "$key in both hashes with same value $hBase{$key}\n";
    } else {
      print "$key in both hashes with different values $hBase{$key} != $hPost{$key}\n";
    }
  } else {
    print "$key in %hBase with value $hBase{$key}\n" if exists $hBase{$key};
    print "$key in %hPost with value $hPost{$key}\n" if exists $hPost{$key};
  }
}