CDO GetAssociatedAppointment method causes duplicate Appointments in OWA

Hi Guys.

I've got some very basic code in VB6.

For Each oRequest In oFolder.Messages
Set oAppointment = oRequest.GetAssociatedAppointment
Set oResponse =
oAppointment.Respond(CdoResponseAccepted)
oResponse.Send
oRequest.Delete
Next

This code runs fine and accepts the meeting request as expected BUT
when the master appointment is updated (via Outlook) and a user
accepts the meeting update via OWA, a duplicate of the updated
appointment is created in the user's calendar.
It also seems that the Global GUID and calendarID are the same for both
appointments in the user's calendar.

I have no idea what I'm leaving off or need to add to the appointment
when I accept it to prevent this from happening.

Many Thanks,
Richard