Which saint holds two keys?

In Matthew 16: 18-19 Our Lord appoints Peter as the head of the Church:

"I also say to you that you are Peter, and upon this rock I will build My church; and the gates of Hades will not overpower it. I will give you the keys of the kingdom of heaven; and whatever you bind on earth shall have been bound in heaven, and whatever you loose on earth shall have been loosed in heaven."

This is the origin of Saint Peter traditionally illustrated holding keys.