This concept is sometimes referred to as a number of different names: Dual Control, Four-Eyes Principle, and Two-Man or Two-Person Principle. The underlying control is that in order to access something it requires two separate people who each hold a different half of the key. Access can only be granted if both halves of the key are used. In terms of Secret Server, these keys are the password for two people: the individual needing to review the report or recording, and the approver with their own password.