No, not all Teflon pans have a non-stick coating on both sides. The non-stick coating is typically applied only to the interior surface of the pan, which is the side that comes into direct contact with food during cooking. The exterior surface of Teflon pans is usually left uncoated or may have a different type of coating or finishing.
The reason for coating only the inside of the pan with the non-stick material is to ensure that food doesn't stick to the cooking surface, making it easier to cook and clean. The exterior of the pan doesn't require a non-stick coating since it doesn't come into contact with the food.
It's essential to follow the manufacturer's instructions and guidelines for the proper use and care of Teflon or non-stick pans to maintain their longevity and effectiveness. Avoid using metal utensils, high heat, and abrasive scrubbers that can damage the non-stick coating and reduce its effectiveness.