title: webpack including react 0.14-beta2 twice in final bundle
body: <p>package.json</p>
  
  <pre><code>"dependencies": {
      "react": "^0.14.0-beta1"}
  </code></pre>
  
  <p>index.js</p>
  
  <pre><code>var React = require('react'),
       ReactDOM = require('react-dom');
  
  window.React = React;
  window.ReactDOM = ReactDOM;
  </code></pre>
  
  <p>webpack config</p>
  
  <pre><code> entry: {
          mainpage: './index.js'
      },
  </code></pre>
  
  <p><strong>Edit :</strong> </p>
  
  <pre><code>npm install react-dom@0.14.0-beta2 --save // solved my issue
  </code></pre>