Incorrect query form causes username conflict

[zebulasampedro]

Internal Server Error: /projects/list/40/allocationrequests/create
Traceback (most recent call last):
  File "/opt/rcamp/lib/python2.7/site-packages/django/core/handlers/base.py", line 132, in get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/opt/rcamp/lib/python2.7/site-packages/django/contrib/auth/decorators.py", line 22, in _wrapped_view
    return view_func(request, *args, **kwargs)
  File "/opt/rcamp/lib/python2.7/site-packages/django/views/generic/base.py", line 71, in view
    return self.dispatch(request, *args, **kwargs)
  File "/opt/rcamp/lib/python2.7/site-packages/django/views/generic/base.py", line 89, in dispatch
    return handler(request, *args, **kwargs)
  File "./projects/views.py", line 274, in post
    return super(AllocationRequestCreateView,self).post(request,*args,**kwargs)
  File "/opt/rcamp/lib/python2.7/site-packages/django/views/generic/edit.py", line 215, in post
    return self.form_valid(form)
  File "./projects/views.py", line 290, in form_valid
    requester = RcLdapUser.objects.get(username=ar.requester.username)
  File "/opt/rcamp/lib/python2.7/site-packages/django/db/models/manager.py", line 127, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/opt/rcamp/lib/python2.7/site-packages/django/db/models/query.py", line 338, in get
    (self.model._meta.object_name, num)
MultipleObjectsReturned: get() returned more than one RcLdapUser -- it returned 2!