During the BlackBerry registration process, NotifyLink gives you the
option of performing OTA (over the air) loads for PIM data, consisting
of calendar, contacts, and tasks.  If the BlackBerry has existing PIM
data NotifyLink won't delete this data prior to the OTA loads
completing as it does on other clients (PPC, Palm).  If the PIM data
previously on the device matches what was brought down from server it
will result in duplication.  Performing another OTA for the type of PIM
that has duplicates will resolve this issue as all existing data at
that time will be removed.