Unique opens and clicks are recorded by the device used to interact with your tracked emails. Unique interactions are characterized by the first time open or click on a particular device.
With privacy friendly aggregate tracking methods, Bananatag tracks devices rather than an particular individual.
While in practice this usually means that a unique open or click corresponds with a unique recipient accessing your message, it's import to note that if the same email is opened (or link clicked) by a specific recipient using two different devices, two unique interactions will be recorded. (A common scenario where this may occur is a recipient clicking a link from their computer, and then clicking the same link again later on their mobile device.)
For multiple opens and clicks on the same device by the same user, repeat opens and clicks are recorded.