title: Confusing "duplicate identifier" Typescript error message
body: <p>Why am I getting this and many more errors of this kind? I am adding a link to the repo as well as key code snippets below. I think I have a basic misunderstanding of how the dependency and "include" chaining works. </p>
  
  <pre><code>csvproc(master)&gt; tsc
  node_modules/typescript/bin/lib.core.d.ts(83,5): error TS2300: Duplicate identifier 'configurable'.
  node_modules/typescript/bin/lib.core.d.ts(84,5): error TS2300: Duplicate identifier 'enumerable'.
  node_modules/typescript/bin/lib.core.d.ts(85,5): error TS2300: Duplicate identifier 'value'.
  node_modules/typescript/bin/lib.core.d.ts(86,5): error TS2300: Duplicate identifier 'writable'.
  </code></pre>
  
  <p><a href="https://github.com/pitosalas/typescript/tree/master/csvproc" rel="noreferrer">All code can be found here</a>.</p>
  
  <p>My tsconfig.json:</p>
  
  <pre><code>{
      "compilerOptions": {
          "module": "commonjs",
          "noImplicitAny": false,
          "outDir": "built/",
          "sourceMap": true,
          "target": "es5"
      }
  }
  </code></pre>
  
  <p>My tsd.json:</p>
  
  <pre><code>{
    "version": "v4",
    "repo": "borisyankov/DefinitelyTyped",
    "ref": "master",
    "path": "typings",
    "bundle": "typings/tsd.d.ts",
    "installed": {
      "node/node-0.10.d.ts": {
        "commit": "6387999eb899d0ba02d37dd8697647718caca230"
      },
      "should/should.d.ts": {
        "commit": "e1182d56ccb192379eade6055d9ba3fb6a0bacc4"
      }
    }
  }
  </code></pre>
  
  <p>My tsd.d.ts:</p>
  
  <pre><code>{
    "version": "v4",
    "repo": "borisyankov/DefinitelyTyped",
    "ref": "master",
    "path": "typings",
    "bundle": "typings/tsd.d.ts",
    "installed": {
      "node/node-0.10.d.ts": {
        "commit": "6387999eb899d0ba02d37dd8697647718caca230"
      },
      "should/should.d.ts": {
        "commit": "e1182d56ccb192379eade6055d9ba3fb6a0bacc4"
      }
    }
  }
  </code></pre>