Preventing duplicate appointments:
When a patient calls, instruct your staff to see if the patient already has an appointment. Start on the "Schedule" screen (top left button). Search the patient list for the patient who is calling. Click on the name. In the box at the bottom left is the next appointment, if one exists.
Searching for duplicates:
For a single patient, this is easy. With the patient name highlighted as above, click on the binoculars icon just below. The right column displays all the appointments, past and future.
If you want to search your whole patient list for duplicates, it is more tedious. Start with the first patient by leaving the search box blank. Click on the first name, then the binoculars icon. Check at the bottom of the appointments listed for duplicates in the future. Use the down-arrow key on your keyboard to scroll through each patient name, checking the appointments for duplicates.