Duplicate reminders on synced events

Quick answer: Set Reminders to Off under What copies look like when the original event already alerts you. Then inspect the actual destination copy. Two alerts can come from an original and its copy, multiple copies, or two calendar apps notifying you about the same event.

Why it happensCopy Anchor Link

The copy is a real event on the destination calendar. If it carries reminders, your phone treats it as its own thing to notify you about, and it has no idea it's a copy of something you're already being reminded about. Two calendars, two alerts, same meeting.

Three settings, and what each does:

Off explicitly disables event reminders on the copy. It is more specific than leaving the reminder unset: Google can disable the event's default reminders and Microsoft has an event-level reminder switch. SYNCDATE writes those settings for an Off copy.

Calendar default leaves the copy's reminders unset, so the destination calendar's own default applies. Most people's calendars have a default of 10 or 30 minutes, so this usually produces the duplicate rather than avoiding it. It's the right choice only when the destination calendar is the one you actually watch and the source is the one you don't.

Same as original carries the original's reminders across. Useful when you want alerts on a work phone for events living on a personal account and you don't get notifications from that account at all.

If you switched to Off and still get two alertsCopy Anchor Link

1. Open each notification and identify the account, calendar and event it refers to. Check whether one comes from the original and one from a copy, or whether two apps show the same event.
2. Confirm Off under Reminders in the sync that writes that destination. On Pro, check the destination's Settings for override too.
3. Inspect the actual destination event's reminder in the provider's own calendar app. Saving a setting and writing the changed copy are separate steps. If the copy has not been rewritten, choose Re-sync, then wait and inspect the result. This can also apply other current appearance settings to existing copies; review them first.
4. Check for another sync service, another sync or an earlier import that left a second copy. Do not delete similar-looking events in bulk. If you are replacing another sync tool, turn its sync off before you rely on this one.

If the event's reminder is off but an alert remains, identify the device, app or calendar notification setting that sends it. An Outlook default reminder is not an unavoidable alert on every copy. Turning off a whole calendar's notifications can also silence its original meetings, so identify the sender before changing those settings.

If an expected Off copy still has a reminder after a successful rewrite, contact support with the sync ID, provider, event time and observed reminder setting. Keep credentials and unnecessary event details out of the message. Do not treat a copy that failed to update as a calendar-default limitation.

Also worth checking: two syncs writing into the same calendar. If you built one sync per source and pointed them all at the same destination, each one is writing its own copy, and Reminders is set per sync.

Known limitationsCopy Anchor Link

• Event reminders and app notifications are separate. Off controls the reminders written to copies; it cannot silence another app or an original event.
• Provider reminder formats differ. Outlook represents one popup; Google can describe several overrides. Check the destination rather than expecting every alert method to travel unchanged.
• Copy carries the reminders that existed when the copy was written. Editing reminders on the original updates the copy on the next run, not at the same moment.
• Reminders is per sync, unless you're on Pro, where you can set it per destination calendar with the Settings for chips.

Check it with a harmless eventCopy Anchor Link

Create one non-sensitive source event with a reminder and no guests. After copying, inspect the destination with Off selected. Check the original and copy separately: displaying both calendars together can make an expected pair look like duplicate data. If you rely on the destination for alerts instead, test Calendar default or Same as original and keep the reminder path you need. Delete the test original and verify cleanup.

Google documents event reminders; Microsoft documents the event reminder fields. These explain the controls; your particular account and device behavior still needs the check above.

Related

Appearance: how copied events look

Every setting that decides what a copy looks like when it lands: title, availability, privacy, colour, guests and reminders.

What SYNCDATE can't do

The limits no plan removes: syncs don't chain, special event types are Google-only, feeds are read-only, and colour is approximate between providers.

Mirror or Push: which one do you need

Push feeds one calendar from another and never touches the source. Mirror goes both ways. How to choose, and what switching later deletes.

Outlook ↔ Google, both directions

Book in Outlook or Google and the other one agrees, with real titles and locations. Works with Microsoft 365 and Outlook.com. Works on the Free plan.

iCloud ↔ Google, both directions

Add an event on your iPhone or your laptop and it shows up on the other, with its real title and location. Works on the Free plan with two calendars.