registrations#create (PG::Error) "ERROR: duplicate key value violates unique constraint

[cgansen]

A PG::Error occurred in registrations#create:

  ERROR:  duplicate key value violates unique constraint "index_admins_on_email"
DETAIL:  Key (email)=(shollins07@gmail.com) already exists.

  vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/postgresql_adapter.rb:1174:in `get_last_result'


-------------------------------
Request:
-------------------------------

  * URL       : http://locations.weconnectchicago.org/admins
  * IP address: 66.87.88.226
  * Rails root: /app
  * Timestamp : 2013-05-18 06:40:59 -0500