We do not allow duplicate events and here are the reasons from them being stopped and you seeing the screen below.
- Duplicate events title on the same day.
- Same events on multiple calendars.
We restrict the submission of the same event to multiple calendars using the same email. If you wish to submit an event to multiple event calendars we advise you should do so by using either unique email address or upgrade to premium where we will syndicate the event to all relevant sites as a service.