Node.js中相同模块是否会被加载多次？

原文链接

[ '/Users/jeffz/Projects/node-test/node_modules',
  '/Users/jeffz/Projects/node_modules',
  '/Users/jeffz/node_modules',
  '/Users/node_modules',
  '/node_modules']

$ npm install express
express[@2](/user/2).5.2 ./node_modules/express 
├── mkdirp[@0](/user/0).0.7
├── qs[@0](/user/0).4.0
├── mime[@1](/user/1).2.4
└── connect[@1](/user/1).8.5

$ npm install mime
mime[@1](/user/1).2.4 ./node_modules/mime 

./node_modules
├── <span style="color: red"><strong>mime</strong>
└── express
    └── node_modules
        ├── mkdirp
        ├── qs
        ├── <span style="color: red"><strong>mime</strong>
        └── connect

module.exports.MyType = function () { }

module.exports.MyType = require("jeffz-a").MyType;

./node_modules
├── jeffz-a
└── jeffz-b
    └── node_modules
        └── jeffz-a

var a = require("jeffz-a");
var b = require("jeffz-b");

console.log(new a.MyType() instanceof a.MyType); // true
console.log(new b.MyType() instanceof b.MyType); // true

console.log(new a.MyType() instanceof b.MyType); // false
console.log(new b.MyType() instanceof a.MyType); // false