Just updated the code for mode so that if there is no mode, that is what gets reported. The original code was always listing the first data item when there was no mode.
The date completed data actually includes the time to the nearest second, but doesn't show it, as the table is already pretty crowded. So, when calculating the mode for time completed, the seconds are disregarded and the mode is based off time completed to the nearest minute. Since the grades generated here are usually all typed just by me, most of the time the time completed results here on this site will show as, no mode, especially if the exercise last for more than a few seconds.