mongoose number subclass fail

mongoosenumbersubclass.js

var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var assert = require('assert')

console.log('\n===========');
console.log('    mongoose version: %s', mongoose.version);
console.log('========\n\n');

var schema = new Schema({
    n1: Number
  , n2: Number
});

var A = mongoose.model('A', schema);
var n = 5;
var a = new A({ n1: n, n2: n });
console.log(typeof a.n1, typeof n)    // object, number
console.log(n == a.n1, a.n1 == a.n2); // true, false