title: Unity - don't load the same assetbundle twice
body: <p>I am having problems with downloading assetbundles.</p>
  
  <p>I get the error:  </p>
  
  <pre><code>The asset bundle 'url/levelpackIphone-Copy.unity3d' can't be loaded because
  another asset bundle with the same files are already loaded
  </code></pre>
  
  <p>I need to check if the asset bundle has already been downloaded. My problem is that I cannot just store the URL, because the file you download can have a different name, but still contain the same content.</p>
  
  <p>Thus somehow I need to check whether the asset bundle already has been downloaded.
  I don't really like to use something like </p>
  
  <pre><code>bundle.Unload(false);
  </code></pre>