You are free to provide one visual per marking area: for example, one logo on the heart and another logo on the back.
However, if you wish to personalize each item in a different way (for example, a unique first name), this is not possible within the same order.
Similarly, if all your items have the same branding area, a single file will be applied to all of them.
To vary the visuals on the same zone, you'll need to place as many orders as there are distinct visuals.