How often can you receive Communion at Mass on the same day?

The Code of Canon Law allows you to receive Communion up to two times in one day (CIC 917). The first time you receive Communion may be at a Mass at which one is assisting (worshiping) or it may be at a Mass where you happen to be in the church at Communion time or it may be outside of a Mass (e.g., at a Communion service). However, the second time you receive Communion it must be at a Mass at which you are assisting (worshiping).