My wife and I have Curve 8310 phones. (Mine seems to be smart---hers not so much
Anyway, I upgraded mine to OS version 126.96.36.199 last weekend. I had no issues.
I upgraded my wife's tonight and now it keeps trying to add duplicate calendar entries and duplicate address book entries too.
I am running Desktop Manager software version 4.3.
I have a backup of her phone, so I went back to that and can now NOT sync without getting the duplicate entries. I went into Backup and Restore-->Advanced and tried to clear the Calendar on the right side of the screen for the device. I then went into the sync settings and told it to do a 1-way copy from the PC to the device. It still just wants to copy the same entries that were duplicates before. I have done a battery reset, disconnected the USB, closed and restarted the desktop manager software.
I was thinking to install the Desktop Manager version 4.7, to clear the device calendar and address book databases and then do a 1-way PC to device sync again.