diff --git a/apps/dav/lib/CalDAV/Reminder/ReminderService.php b/apps/dav/lib/CalDAV/Reminder/ReminderService.php
index 9ededb8d01592..db20d923e539f 100644
--- a/apps/dav/lib/CalDAV/Reminder/ReminderService.php
+++ b/apps/dav/lib/CalDAV/Reminder/ReminderService.php
@@ -467,7 +467,16 @@ private function getRemindersForVAlarm(VAlarm $valarm,
 	 * @param array $reminders
 	 */
 	private function writeRemindersToDatabase(array $reminders): void {
+		$uniqueReminders = [];
+		$seen = [];
 		foreach ($reminders as $reminder) {
+			$key = $reminder['notification_date']. $reminder['event_hash'];
+			if(!isset($seen[$key])) {
+				$seen[$key] = true;
+				$uniqueReminders[] = $reminder;
+			}
+		}
+		foreach ($reminders as $uniqueReminders) {
 			$this->backend->insertReminder(
 				(int) $reminder['calendar_id'],
 				(int) $reminder['object_id'],