They're equal if, as you say, they have the same number of keys AND all the keys in one are in the other.

my $areEqual=1;

if(keys %hash1 == keys %hash2) {
    foreach my $key(keys %hash1) {
        if(!exists $hash2{$key}) {
             $areEqual=0;
             last;
        }
    }
}

if($areEqual) {
    print "ARE ";
} 
else {
    print "ARE NOT ";
}

print "equal\n";
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