[Vuejs]-SPA Authentication on multiple cards

You should probably keep the authentication state into Vuex. For the tab sync, there are some packages that may be useful here: https://github.com/vuejs/awesome-vue#sync-between-tabs

If you want to have several authenticated users, you may think about some logic to handle it into your localStorage or alike. But this kind of question is out of scope (opinion-based) and would be closed. If you want to achieve this, come back with some code sample that you’ve already tried.