Django URLs with/without proxy server

Question

I have two Django apps (say, app1 and app2) hosted on the same machine using Apache mod_wsgi. These two apps are hosted on two different environments:

1. On a physical server where only these two apps are hosted. They are accessed as http://www.example.com/app1/app1/ and http://www.example.com/app2/app2/.
2. In the second environment there is a proxy server. A separate web page on that server is accessed as http://www.domain.com/. This links to the above two apps (now hosted on a single virtual machine) as http://www.domain.com/id1/ and http://www.domain.com/id2/

The URLconf file looks like:

urlpatterns = patterns('',
    (r'^admin/', include(admin.site.urls)),
    (r'^app1/', include('project.app1.urls')),        
)

The problem is, this URL configurations works in the environment 1, but not in the environment 2. Now, if I do something crazy in the environment 2 such as

 urlpatterns = patterns('',
    (r'^admin/', include(admin.site.urls)),
    (r'^app1/app1/app1/', include('project.app1.urls')),        
    (r'^app1/app1/', include('project.app1.urls')),        
    (r'^app1/', include('project.app1.urls')),        
 )

then the application works. In the env. 2, the app is accessed as http://www.domain.com/id1/app1/app1/.

I couldn't understand why we need to prefix app1 in the URL so many times. In other words, why (how) this works.

Could someone clarify on this? Also, note that all configurations need to be done on the virtual machine. I don't have access to the proxy server.