title: Multiple Typescript modules without duplicate identifier errors
body: <p>I have split a project in to multiple bower modules all of which need to reference underscore.d.ts file</p>
  
  <pre><code>- bower_components
   |- module_a
      |- src
         |- externl-commonjs.ts
   |  |- typings
   |     |- underscore
   |- module_b
      |- src
         |- externl-commonjs.ts
      |- typings
         |- underscore
  - src
    |- externl-commonjs.ts
  - typings
    |- underscore
  </code></pre>
  
  <p>I can successfully compile module_a and module_b on their own... but when they are in a project like above I get Duplicate identifier errors because of the multiple <code>/// &lt;reference</code>s to underscore.d.ts within each external module file.</p>
  
  <p>How would you work around this and have a single source of truth for underscore.d.ts.</p>