title: Only one instance of babel-polyfill is allowed
body: <p>I am getting the following error</p>
  
  <pre><code>Uncaught Error: only one instance of babel-polyfill is allowed
      at Object.eval (index.js?db4d:10)
      at eval (index.js:29)
      at Object../node_modules/babel-polyfill/lib/index.js (vendors.js?3b19ee46035be2acbd36:310)
      at __webpack_require__ (vendor.js?3b19ee46035be2acbd36:79)
      at Object.4 (vendor.js?3b19ee46035be2acbd36:165)
      at __webpack_require__ (vendor.js?3b19ee46035be2acbd36:79)
      at checkDeferredModules (vendor.js?3b19ee46035be2acbd36:46)
      at vendor.js?3b19ee46035be2acbd36:152
      at vendor.js?3b19ee46035be2acbd36:155
  </code></pre>
  
  <p>Here is my <code>package.json</code>:</p>
  
  <pre><code>{
    "name": "something",
    "version": "1.0.0",
    "description": "something",
    "main": "index.js",
    "scripts": {
      "test": "cross-env TZ=utc jest --verbose",
      "dev": "webpack --mode development",
      "build": "webpack --mode production",
      "start": "webpack-dev-server --hot --inline --mode development"
    },
    "author": "Great Company",
    "license": "UNLICENSED",
    "private": true,
    "jest": {
      "globals": {
            ...
        }
      },
      "transform": {
        "^.+\\.js$": "babel-jest",
        "^.+\\.tsx?$": "ts-jest"
      },
      "setupTestFrameworkScriptFile": "./setup-jasmine-env.js",
      "testRegex": "(/__tests__/.*|(\\.|/)(test|spec))\\.(jsx?|tsx?)$",
      "moduleFileExtensions": [
        "ts",
        "tsx",
        "js",
        "jsx",
        "json",
        "node"
      ],
      "moduleNameMapper": {
        "^.+\\.(jpg|svg|png|gif|eot|otf|webp|svg|ttf|woff|woff2|mp4|webm)$": "jest-static-stubs/png"
      },
      "collectCoverage": true,
      "coverageReporters": [
        "html"
      ]
    },
    "dependencies": {
      "@types/react": "^16.4.4",
      "@types/react-dom": "^16.0.6",
      "axios": "0.15.3",
      "babel-polyfill": "6.26.0",
      "bootstrap": "3.3.7",
      "detect-browser": "2.1.0",
      "react": "15.6.2",
      "react-bootstrap": "0.30.10",
      "react-datepicker": "0.58.0",
      "react-dom": "15.6.2",
      "react-redux": "5.0.6",
      "react-router": "3.2.0",
      "react-router-redux": "4.0.8",
      "react-select": "1.1.0",
      "redux": "3.7.2",
      "redux-thunk": "2.2.0",
      "reselect": "3.0.1"
    },
    "devDependencies": {
      "@types/jasmine": "^2.8.8",
      "@types/jest": "^23.1.4",
      "@types/node": "^10.5.1",
      "awesome-typescript-loader": "^5.2.0",
      "babel-core": "^6.26.3",
      "babel-jest": "19.0.0",
      "babel-loader": "^7.1.4",
      "babel-preset-es2015": "6.24.1",
      "babel-preset-react": "6.24.1",
      "babel-preset-stage-2": "6.24.1",
      "cross-env": "5.1.3",
      "css-loader": "0.26.4",
      "deep-freeze": "0.0.1",
      "extract-text-webpack-plugin": "2.1.2",
      "file-loader": "^1.1.11",
      "html-webpack-plugin": "^3.2.0",
      "jasmine-reporters": "2.3.0",
      "jest": "^23.3.0",
      "jest-static-stubs": "0.0.1",
      "mini-css-extract-plugin": "^0.4.0",
      "optimize-css-assets-webpack-plugin": "1.3.2",
      "redux-devtools-extension": "2.13.2",
      "source-map-loader": "^0.2.3",
      "style-loader": "0.13.2",
      "ts-jest": "^23.0.0",
      "typescript": "^2.9.2",
      "url-loader": "^1.0.1",
      "webpack": "^4.12.2",
      "webpack-cli": "^3.0.8",
      "webpack-dev-server": "^3.1.4"
    }
  } 
  </code></pre>
  
  <p>In my <code>webpack.config.js</code>, I have:</p>
  
  <pre><code>const config = {
      entry: {
          main: path.join(SRC_DIR, 'app', 'index.js'),
          vendor: [
              'axios',
              'babel-polyfill',
              'react',
              'react-bootstrap',
              'react-dom',
              'react-redux',
              'react-router',
              'react-router-redux',
              'react-select',
              'redux',
              'redux-devtools-extension',
              'redux-thunk',
              'reselect'
          ]
      },
      ...
      plugins: [
          new HtmlWebpackPlugin({
              template: path.join(SRC_DIR, 'static', 'index.html'),
              hash: true,
              inject: false
          }),
          new MiniCssExtractPlugin('css/styles.css')
      ]
  </code></pre>
  
  <p>I tried removing the <code>HtmlWebpackPlugin</code> entirely and adding the <code>inject: false</code> field and the error still occurs. Any help would be greatly appreciated.</p>