How to read the backups history of my iPhone?
iTunes only saves 1 active-backup from your iPhone. Each time you back it up, it is archiving the data that was on the device at the time, this is where the dating of the previous backup comes into play.

The dated backups are typically those that have been used for a restore. When you do this the restored backup is archived with the date of the restore and a new rolling backup is created. With iTunes for Mac, you can also trigger the archive process manually. You can select and delete older backup as you chose, though I would suggest you keep one or two.

This "archiving" is Apple's way of "copying or duplicating" an iTunes backup file without the user having to physically rename that backup file or physically moving the backup file into another location. 

It's similar to how Time Machine on a Mac performs when archiving files.