title: npm WARN The package is included as both a dev and production dependency
body: <p>When running <code>npm install</code></p>
  
  <p>I got these warning:</p>
  
  <pre><code>npm WARN The package babel-core is included as both a dev and production dependency.
  npm WARN The package babel-loader is included as both a dev and production dependency.
  npm WARN The package babel-preset-react is included as both a dev and production dependency.
  npm WARN The package redux-thunk is included as both a dev and production dependency.
  npm WARN The package uglifyjs is included as both a dev and production dependency.
  
  up to date in 7.183s
  npm WARN The package babel-core is included as both a dev and production dependency.
  npm WARN The package babel-loader is included as both a dev and production dependency.
  npm WARN The package babel-preset-react is included as both a dev and production dependency.
  npm WARN The package redux-thunk is included as both a dev and production dependency.
  npm WARN The package uglifyjs is included as both a dev and production dependency.
  </code></pre>
  
  <p><code>package.json</code> file:</p>
  
  <pre><code>{
   ...
    "dependencies": {
      "axios": "^0.15.3",
      "babel-core": "^6.10.4",
      "babel-loader": "^6.2.4",
      "babel-polyfill": "^6.9.1",
      "babel-preset-es2015": "^6.9.0",
      "babel-preset-react": "^6.11.1",
      "babel-preset-stage-2": "^6.24.1",
      "babel-register": "^6.9.0",
      "bluebird": "^3.5.0",
      "bootstrap-sass": "^3.3.7",
      "classnames": "^2.2.5",
      "console-polyfill": "^0.2.3",
      "cross-env": "^1.0.8",
      "css-loader": "^0.23.1",
      "deepmerge": "^1.3.2",
      "dom-helpers": "^3.0.0",
      "expect": "^1.20.1",
      "fuzzy": "^0.1.3",
      "moment": "^2.18.1",
      "node-libs-browser": "^1.0.0",
      "node-sass": "^3.8.0",
      "react": "^15.1.0",
      "react-addons-shallow-compare": "15.4.0",
      "react-addons-test-utils": "^15.1.0",
      "react-axios": "0.0.9",
      "react-bootstrap-daterangepicker": "^3.2.2",
      "react-daterange-picker": "^1.1.0",
      "react-dom": "^15.1.0",
      "react-draggable": "^2.2.3",
      "react-redux": "^4.4.8",
      "react-router": "^3.0.2",
      "react-virtualized": "^8.5.2",
      "redux": "^3.6.0",
      "redux-logger": "^2.6.1",
      "redux-promise": "^0.5.3",
      "redux-promise-middleware": "^4.2.0",
      "redux-thunk": "^2.1.0",
      "sass-loader": "^4.0.0",
      "style-loader": "^0.13.1",
      "uglifyjs": "=2.4.10",
      "webpack-dev-middleware": "^1.6.1",
      "webpack-dev-server": "^1.14.1",
      "webpack-hot-middleware": "^2.11.0"
    },
    "devDependencies": {
      "assets-webpack-plugin": "^3.5.1",
      "babel-core": "^6.24.1",
      "babel-loader": "^7.0.0",
      "babel-plugin-add-module-exports": "^0.2.1",
      "babel-plugin-react-transform": "^2.0.2",
      "babel-plugin-transform-decorators-legacy": "^1.3.4",
      "babel-preset-es2016": "^6.24.1",
      "babel-preset-react": "^6.24.1",
      "babel-preset-stage-3": "^6.24.1",
      "didyoumean": "^1.2.1",
      "extract-text-webpack-plugin": "^1.0.1",
      "glob": "^7.1.1",
      "postcss-loader": "^1.3.0",
      "purifycss-webpack-plugin": "^2.0.3",
      "react-transform-hmr": "^1.0.4",
      "redux-thunk": "^2.2.0",
      "uglifyjs": "=2.4.10",
      "webpack": "^1.15.0",
      "webpack-cleanup-plugin": "^0.5.1",
      "webpack-split-chunks": "^0.1.1"
    }
  }
  </code></pre>
  
  <p>Noticed that there were different versions installed. What exactly happens when there are two versions of the same package installed for dev and prod? Is this normal behavior? Should I get rid of the dupe references in the package.json file? </p>