title: WPF Prism Loading views to Region, previous view is not removed
body: <p>I'm new to WPF Prism, my problem is this.</p>
  
  <ol>
  <li><p>I have a region and I register a view like this</p>
  
  <pre><code>_container.RegisterType(typeof(Object), typeof(MgpOptions),typeof(MgpOptions).FullName);
  
  _container.RegisterType(typeof(Object), typeof(SgpOptions), typeof(SgpOptions).FullName);
  </code></pre></li>
  <li><p>Then I navigate to it like this</p>
  
  <pre><code>_regionManager.Regions[RegionNames.AppBarRegion].NavigationService.RequestNavigate(typeof(MgpOptions).FullName);`
  </code></pre></li>
  <li><p>On sum button click event I navigate to SgOptions View like this</p>
  
  <pre><code>_regionManager.Regions[RegionNames.AppBarRegion].RequestNavigate(typeof(SgpOptions).FullName);
  </code></pre></li>
  </ol>
  
  <p>My problem is when the 3rd step completed both views appear in the region 
  I just want to show one View at a time.</p>