When you order the bundle SKU in CCW (Cisco's ordering tool for partners), it's required to order two appliances and associated subscriptions. If you order them that way, the price for subscriptions on the second appliance will be discounted.
Subscriptions available include Protect and Control (also known as IPS), URL Filtering and Malware. They can be ordered individually or in combination and in term lengths of 1, 3 or 5 years.
