title: require.js multiple including
body: <p>I try to search the issue I'm facing, but I found it's hard to get an answer, so I ask here.</p>
  <p>I use <code>require.js</code> to decompose my project.</p>
  <p>the structure is:</p>
  <pre><code>main.js 
  
  a.js
  
  b.js
  
  c.js
  </code></pre>
  <p>and the dependencies is:</p>
  <blockquote>
  <p>c needs a</p>
  <p>b needs a</p>
  <p>main needs a, b, c</p>
  </blockquote>
  <p>so <code>a.js</code> will be included for twice, it works correctly, but I don't know whether this is the best way to use require.js</p>