my @common = grep exists $hash2{$_}, keys %hash1;
my @unique1 = grep !exists $hash2{$_}, keys %hash1;
my @unique2 = grep !exists $hash1{$_}, keys %hash2;

##</code><code>##

my %t;
$t{$_} .= "1" for keys %hash1;
$t{$_} .= "2" for keys %hash2;