ID on event notification different from published ID

I am having a small problem with the notifications sent out when a new event is created.

For example the link on the email sent out was:

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View this Event: http://buddypressinstallation.org.uk/groups/groupname/calendar/event/92/

But the actual link to view the event is:

http://buddypressinstallation..org.uk/groups/groupname/calendar/event/4/

I am not sure why the email notification ID would be different from the published ID.