title: Multiple dex files error when compiling with ant or Eclipse
body: <p>I am unable to build my application
  I am running the latest build tools downloaded today, this started happening after the update.</p>
  
  <pre><code>-dex:
     [dex] Converting compiled files and external libraries into 
           /Users/rob/Repos/my_app/bin/classes.dex...
      [dx] 
      [dx] UNEXPECTED TOP-LEVEL EXCEPTION:
      [dx] com.android.dx.util.DexException: Multiple dex files define 
           Lcom/robaldred/myapp/About$1;
  </code></pre>
  
  <p>I have tried cleaning and rebuilding, I've also tried in Eclipse but it gives the same error.
  Anyone got any ideas? I'm at a brick wall here now.</p>