如何解决django.core.exceptions.ImproperlyConfigured：应用程序标签不唯一，重复：帐户django 1.5

Question

File "manage.py", line 15, in <module>
  execute_from_command_line(sys.argv)
File "/usr/local/lib/python2.7/dist-packages/django/core/management/__init__.py", line 364, in execute_from_command_line
  utility.execute()
File "/usr/local/lib/python2.7/dist-packages/django/core/management/__init__.py", line 338, in execute
  django.setup()
File "/**strong text**usr/local/lib/python2.7/dist-packages/django/__init__.py", line 27, in setup
  apps.populate(settings.INSTALLED_APPS)
File "/usr/local/lib/python2.7/dist-packages/django/apps/registry.py", line 89, in populate
  "duplicates: %s" % app_config.label)
django.core.exceptions.ImproperlyConfigured: Application labels aren't unique, duplicates: account

如何解决这个问题？什么地方出了问题或怎么回事？