When something's wrong
Calendar events show up twice
Duplicates after connecting a calendar have three usual causes.
Cause and fix
The same calendar is subscribed twice on the device. A work calendar added both directly and through an account subscription appears twice to every app, not just NewTwos. Fix it in your device's calendar settings, then deselect one in NewTwos.
Reminders are being pushed out and read back. With Settings Calendar & Reminders Push all reminders to connected calendar on, NewTwos writes reminders to your calendar, and then reads that calendar. Turn push off and see whether duplicates stop.
Two calendars genuinely contain the same event. A shared event in both your personal and work calendars is two real events. Deselect one of those calendars in NewTwos.
Cleaning up
Disconnecting offers to remove the events NewTwos created. Events it did not create are untouched, since only its own carry a marker.
That marker matters: it is what makes cleanup safe rather than a bulk delete of your calendar.
Preventing it
- Select as few calendars as possible when connecting.
- Leave push-to-calendar off unless someone else needs to see your reminders.
- Do not connect the same account on two devices and push from both.
What to send support
Which calendars are selected, whether push is on, one duplicated event title, and whether the duplicate appears in your calendar app as well or only in NewTwos.