I assume you've something like the below in the User model; because of this, you are getting this routing error.
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable,
:validatable, :omniauthable,
:omniauth_providers => [:facebook],
:omniauth_providers => [:twitter]
Change it to the following:
devise :database_authenticatable, :registerable,
:recoverable, :rememberable, :trackable,
:validatable, :omniauthable,
:omniauth_providers => [:facebook, :twitter]