Django 1.9 Application labels aren't unique, duplicates: django

[x007007007]

Traceback (most recent call last):
  File "/Users/xxc/.virtualenvs/funnyface/lib/python2.7/site-packages/django/utils/autoreload.py", line 226, in wrapper
    fn(*args, **kwargs)
  File "/Users/xxc/.virtualenvs/funnyface/lib/python2.7/site-packages/django/core/management/commands/runserver.py", line 109, in inner_run
    autoreload.raise_last_exception()
  File "/Users/xxc/.virtualenvs/funnyface/lib/python2.7/site-packages/django/utils/autoreload.py", line 249, in raise_last_exception
    six.reraise(*_exception)
  File "/Users/xxc/.virtualenvs/funnyface/lib/python2.7/site-packages/django/utils/autoreload.py", line 226, in wrapper
    fn(*args, **kwargs)
  File "/Users/xxc/.virtualenvs/funnyface/lib/python2.7/site-packages/django/__init__.py", line 18, in setup
    apps.populate(settings.INSTALLED_APPS)
  File "/Users/xxc/.virtualenvs/funnyface/lib/python2.7/site-packages/django/apps/registry.py", line 89, in populate
    "duplicates: %s" % app_config.label)
django.core.exceptions.ImproperlyConfigured: Application labels aren't unique, duplicates: django

my setting file like:

INSTALLED_APPS = [
      ....
    'lettuce.django',
]

[x007007007]

My config duplicate installed apps, sorry