In outlook, not worries, but in both the Samsung and Google Calendar I get duplicates. I have unclicked all calendars and no matter which one I select I get exact duplicates for every event. I deleted outlook from phone, no difference. I have restarted. I have made sure that there is only one email account for the office 365 source calendar.
In short, if I start with blank calendar and click anyone claendar, I get duplicate events.