title: Why can't I register multiple Django ModelAdmin with same Model?
body: <p>I have the following ModelAdmin:</p>
  
  <pre><code>class EventAdmin(admin.ModelAdmin):
      # ModelAdmin config
  
      def queryset(self, request):
          queryset = super(EventAdmin, self).queryset(request)
          return queryset.exclude(date_end__lt=date.today())
  
  admin.site.register(Event, EventAdmin)
  </code></pre>
  
  <p>Now I want to add a model to manage archived (older than today) events.</p>
  
  <pre><code>class EventArchiveAdmin(admin.ModelAdmin):
      # ModelAdmin config
  
      def queryset(self, request):
          queryset = super(EventArchiveAdmin, self).queryset(request)
          return queryset.filter(date_end__lt=date.today())
  
  admin.site.register(Event, EventArchiveAdmin)
  </code></pre>
  
  <p>But if I try to do so I get <em>AlreadyRegistered</em> exception.</p>
  
  <p>Why can't I implement another ModelAdmin with same Model and how can I get different <em>admin views</em> of the same model?</p>
  
  <p>I know I can implement a custom <code>list_filter</code> in my class but I'd like to keep things separated in different pages.</p>