First, some terminology: we will consider a “duplicate” to be the same event on the same calendar. CalendarBridge has been designed to prevent duplicates. But there are some situations that cause users to believe we have created duplicates.
Viewing Both calendars at the same time
If you have two-way sync connection between calendar A and calendar B, but have one of your calendar apps set to show both calendars, there will appear to be duplicates. But they are not true duplicates — one of the events is the original event on the source calendar and the other event is the event copy on the destination calendar. The solution here is to hide one of the calendars — go into the settings on your calendar app and configure it to show only one of the two calendars (in most apps this involves unchecking a checkbox next to the calendar you want to hide).
Viewing both calendars in the same app looks like duplicates, but one is the original and one is the copy.
Having the Same Event Natively on Both Calendars
If you copy “Event” from Calendar A to Calendar B outside of CalendarBridge, then we will see “Event” on calendar A as being a different event than “Event” on calendar B. If you then create a sync connection from Calendar A to Calendar B, Calendar B will end up with both: “Event” (the copy made outside of CalendarBridge); and “Event (copy)” (the copy of “Event” from Calendar A that we made). So, the solution here is to delete any duplicate events before creating a CalendarBridge sync connection.
If the event is natively on both calendars, then it will result in having both the original event and an event copy on the same calendar.
Using the software Simple Practice
Simple Practice is the only software we are aware of that causes CalendarBridge to create actual duplicates is Simple Practice. Simple Practice overwrites our events and does not preserve the metadata that is used to keep track of copies. In other words, CalendarBridge is not compatible with Simple Practice.