Warning message when duplicating

[GustavoCaso]

Having this code

class AllowedParams < HashMap::Base
  property :baobab_id, from: :id
  property :timezone, from: :time_zone
  from_child :coordinates do
    properties :latitude, :longitude
  end
  properties :name, :phone, :fax, :address, :timezone, :city, :main_city, :state,
    :state_code, :postal_code, :country, :country_code, :coordinates
end

Having timezone multiple times, it would be nice to have a warning message