title: Having two tab navigation bars in React Navigation
body: <p>I want to create an app, that has both a fixed bottom and top tab navigation bar.
  See image: <a href="https://i.stack.imgur.com/jg4LM.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/jg4LM.png" alt="enter image description here" /></a></p>
  <p>After I finished the bottom navigation bar I tried the following in my App.js file:</p>
  <pre><code>return(
      &lt;NavigationContainer&gt;
          &lt;Tab.Navigator&gt;    //top navbar
              &lt;Tab.Screen /&gt;
              ...
          &lt;/Tab.Navigator&gt;
          &lt;Tab.Navigator&gt;    //bottom navbar
              &lt;Tab.Screen /&gt;
              ...
          &lt;/Tab.Navigator&gt;
      &lt;/NavigationContainer&gt;
  )
  </code></pre>
  <p>However, I get the error, that another navigator is already registered in this container and that I should not have multiple navigators under a single NavigationContainer.
  I found multiple guides about nesting tab and stack navigators, but how do I nest multiple tab navigators, that both update the central screen?</p>