title: All my code runs twice when compiled by Webpack
body: <p>When I build my js bundle with webpack using <code>webpack-dev-server</code> my code runs twice every time. Not sure how to fix it.</p>
  
  <p><a href="http://i.stack.imgur.com/Sz5IV.png" rel="noreferrer">Screenshot of Developer Tools console</a></p>
  
  <p>My webpack config:</p>
  
  <pre><code>var path = require('path');
  var webpack = require('webpack');
  var HtmlWebpackPlugin = require('html-webpack-plugin');
  var CopyWebpackPlugin = require('copy-webpack-plugin');
  
  module.exports = {
    devtool: 'cheap-eval-sourcemap',
    entry: [
      'webpack-dev-server/client?http://localhost:8080',
      'webpack/hot/dev-server',
      path.join(__dirname, '../src/main')
    ],
    output: {
      path: path.join(__dirname, '../dist'),
      filename: 'bundle.js'
    },
    plugins: [
      new webpack.HotModuleReplacementPlugin(),
      new webpack.optimize.OccurenceOrderPlugin(),
      new HtmlWebpackPlugin({
        template: path.join(__dirname, '../src/index.html')
      }),
      new CopyWebpackPlugin([
        {
          from: path.join(__dirname, '../assets'),
          to: path.join(__dirname, '../dist/assets')
        }
      ])
    ],
    devServer: {
      contentBase: path.join(__dirname, '../dist'),
      outputPath: '/lol',
      hot: true
    },
    module: {
      loaders: [
        {
          test: /\.js$/,
          loaders: ['babel-loader'],
          include: path.join(__dirname, '../src')
        }
      ]
    }
  };
  </code></pre>