An Athlete cannot be in two simultaneous periods.
A warning message will pop up, if you try to add an Athlete that already occupies a concurrent period:
To rectify it:
- Remove the Athlete from the concurrent period, or
- Adjust the new period's start and end time so it does not overlap with the current period to which the Athlete has already been added, or
- Remove the Athlete from a concurrent period in another activity that might be running at the same time.
For more information see these guides: