The Switch maintains two versions of the Switch image in its permanent storage. One image is the active image, and the second image is the backup image. The Dual Image screen enables the user to select which partition will be set as active after the next reset. The Switch boots and runs from the active image. If the active image is corrupt, the system automatically boots from the non-active image.
This acts as a failsafe when you wish to upgrade the firmware. Due to some reason, if you would like to revert back to an older firmware, you can easily perform that by changing the active partition.
Navigate to MANAGE | Switch Controller | Switches tab and select the Firmware tab.
You can see the current active partition and the corresponding firmware associated with it.
If you wish to revert to an older firmware, you can click on the Change Active Partition option.
NOTE: If there are features configured which are not available on the older firmware, those settings will be removed. The partitions will use the latest configuration and only the firmware will be changes. It is not the same as creating backup settings and going back to an older configuration.