metadata - What do these six lenses in EXIF mean, for the iPhone 7 Plus?

The iPhone 7 Plus has two back cameras, but the lens field in EXIF has six different values:

• iPhone 7 Plus back camera 3.99mm f/1.8


• iPhone 7 Plus back camera 6.6mm f/2.8


• iPhone 7 Plus back dual camera 3.99mm f/1.8


• iPhone 7 Plus back dual camera 6.6mm f/2.8


• iPhone 7 Plus back iSight Duo camera 3.99mm f/1.8


• iPhone 7 Plus back iSight Duo camera 6.6mm f/2.8

Why are there so many, and how do they correspond to the two physical lenses?