"requirejs(dep)" loads dep twice

dep.js

console.log('loaded "dep"');

index.js

requirejs.config({
  nodeRequire: require,
  baseUrl: '.'
});

requirejs('dep');

package.json

{
  "name": "requirejs-node-duplication-sample",
  "version": "1.0.0",
  "devDependencies": {
    "requirejs": "2.1.17"
  }
}

Run node index.js and watch "dep" get printed twice.