Using multiple slugs in a url

I want to keep my urls dynamic as well as clean. Therefore I'm using slugs.

My problem right now is, that I get the following error:

redefinition of group name 'slug' as group 2; was group 1 at position 42

I think I get that error, because I have two slugs in my chain. For reference I have a ListView into ListView into an UpdateView, alls importet from django.views.generic. The first list view gives me the first slug and the update view the second.

Here is the url pattern (spread across the apps):

First list view:

urlpatterns = [
    url(r'^$', RestaurantListView.as_view(), name='restaurant-list'),
    url(r'^(?P<slug>[\w-]+)/menus/', include('menu.urls', namespace='menu')),
]

Second list view:

urlpatterns = [
    url(r'^$', MenuListView.as_view(), name='menu-list'),
    url(r'^(?P<slug>[\w-]+)/', MenuUpdateView.as_view(), name='menu-detail'),
]

In the templates I get the objects via:

<li><a href='{{obj.get_absolute_url}}'> {{obj}} </a></li>

Which I have defined in the respective models:

def get_absolute_url(self):
        return reverse('restaurants:menu:menu-detail', kwargs={'slug': self.slug})

and

def get_absolute_url(self):
        return reverse('restaurants:menu:menu-list', kwargs={'slug': self.slug})

So the resulting pattern at the end is:

restaurants/(?P<slug>[\w-]+)/menus/(?P<slug>[\w-]+)/

How can I fix it so that I don't get the error anymore?

Solution

from django.conf.urls import url

from . import views

urlpatterns = [
    url(r'^articles/2003/$', views.special_case_2003),
    url(r'^articles/(?P<year>[0-9]{4})/$', views.year_archive),
    url(r'^articles/(?P<year>[0-9]{4})/(?P<month>[0-9]{2})/$', views.month_archive),
    url(r'^articles/(?P<year>[0-9]{4})/(?P<month>[0-9]{2})/(?P<day>[0-9]{2})/$', views.article_detail),
]

for more details https://docs.djangoproject.com/en/1.11/topics/http/urls/