The two digit displays a few things.
1) Alternate battery voltage Integer & decimal for precise voltage calibration to compensate for cabling & connection losses . eg 12.74
2) Single integer & decimal for current load setting up to 9.9A.
3) Cumulative Ah while running.
4) Undervolt 'Lo', to avoid testing an undercharged battery.
5) Hi Ah >99 - 'Hi'
6) 'UP' when ready to uplink the discharge log to PC
The Design files link contains build instructions, How it works, , BOM, HEX code and parts sourcing from Jameco.