# Terminal tab 1
cd vue-loader-hmr-bug
npm install
npm run serve
# Terminal tab 2
cd app1
npm install
npm run serve
# Terminal tab 3
cd app2
npm install
npm run serve
Then open http://localhost:9000 in a browser. Notice how only one of the apps is mounted twice and the other isn't mounted at all.
Then go to the vue.config.js in both apps and uncomment the code in there that disables HMR. Restart the servers for each app, and the bug is fixed: