Making change to Public calendar event

[Rexxx]

I have a Public calendar and when I send a meeting request to it then later decide to either cancel it or change it the Public calendar treats the change by creating a new item on the calendar as opposed to modifying the original or deleting it. So when a change happens there becomes at least two appointments on the Public calendar the original and the updated original or cancellation. Any ideas how to correct this? One thing I noticed is that if you open the original event in the Public calendar the event says out-of-date. So the Public calendar marks the original but rather then remove it or modify it the Public calendar creates a new item. Perhaps you may know a rule that can be added to the Public calendar to remove out-of-date items. If so, how is this rule created?