Authentication systems typically fall into two categories: deterministic systems that resolve identity with certainty and probabilistic systems that rely on interpretation or behavioral signals. Understanding the difference between these models is critical when evaluating technologies used for product authentication, infrastructure verification, and security-sensitive environments.

QR codes are widely used for logistics, marketing, and product engagement, but they were never designed to prevent cloning. Because QR codes contain readable identifiers, duplicating the image typically preserves the same function. This article explains how QR code cloning works, why serialization alone does not solve the problem, and what authentication systems must do differently to detect duplication.