I get the following error when instantiating a Django form with a the constructor overriden:

__init__() got multiple values for keyword argument 'collection_type'

The __init__() function (shown below) is exactly as written this but with # code replaced with my logic. Asside from that I am essentially overriding the form's (which is a ModelForm) constructor.

def __init__(self, collection_type, user=None, parent=None, *args, **kwargs):
    # code
    super(self.__class__, self).__init__(*args, **kwargs)

The call that creates the error is shown here:

form = CreateCollectionForm(
    request.POST, 
    collection_type=collection_type, 
    parent=parent, 
    user=request.user
)

I cannot see any reason why the error is popping up.

EDIT: Here is the full code for the constructor

def __init__(self, collection_type, user=None, parent=None, *args, **kwargs):
    self.collection_type = collection_type
    if self.collection_type == 'library':
        self.user = user
    elif self.collection_type == 'bookshelf' or self.collection_type == 'series':
        self.parent = parent
    else:
        raise AssertionError, 'collection_type must be "library", "bookshelf" or "series"'
    super(self.__class__, self).__init__(*args, **kwargs)

EDIT: Stacktrace

Environment:

Request Method: POST
Request URL: http://localhost:8000/forms/create_bookshelf/hello
Django Version: 1.1.1
Python Version: 2.6.1
Installed Applications:
['django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.sites',
 'libraries',
 'users',
 'books',
 'django.contrib.admin',
 'googlehooks',
 'registration']
Installed Middleware:
('django.middleware.common.CommonMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware'
django django-forms
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