Coverage is an estimate of the agents’ contributions to the presented activities, and is displayed in the time format (hh:mm).
These contributions are based on the agents' scheduled activities for each time interval, and on any schedule items that affect these scheduled activities for an interval (such as a break that occurs during only part of an interval).
When looking at Multi site activities, the data is aggregated to arrive at the final metric. Individual activites are not aggregated.
If you feel you still have discrepancies, please open a Case with Customer Care and we can investigate for you.