To add a second shift in the same day for an employee:
In your Scheduler, hover your mouse over an existing shift.
Click the + button that appears on the shift.
Type the name of the second shift.
Click the shift to confirm its selection.
The second shift will be set below the original shift.
If the second shift is added to a shift pattern, it will not be included in future iterations of the shift pattern. The second shift acts as a "one off" for the week in which it was set. In order to update shift patterns with new or modified shifts, a new pattern must be created in the shift patterns screen.