Have you been getting duplicate contact and calendar entries on your blackberry after installing Google Sync? (See further follow-up in comments on multiple calendars and how to fix)

The reason? It is built in to all the latest blackberries!

As soon as you add your Gmail account to your blackberry BIS profile (Blackberry BIS is simply the server program for the average individual run by your ISP that holds, and pushes, emails to your public blackberry. Corporate email will use what is called a BES) it is already set up to sync and backup contacts and calendar appointments. When you install and run Google sync it conflicts with this process.

The built in sync is set up like so:

  1. Appointments/Contacts made on your phone are instantly pushed to Gmail
  2. Appointments/Contacts made on Gmail are pull to your phone
  3. All email features are push and instant.

So what is happening when you use Google sync?

  1. Your blackberry makes a new calendar appointment, it syncs it with gmail
  2. Google Sync will find that there is a new appointment, and sync with gmail
  3. There are now two appointments on gmail.
  4. Your blackberry will pull any updates from the gmail server, finding the “new” item
  5. There is now a duplicate item which GS will find and sync with the gmail server.
  6. etc.

Hope this helps any frustrated people out there. If you want to change these behaviors and have a torch for example, hit the menu (blackberry) button, select options, click on the gmail calendar under “accounts”, and modify the “Wireless Synchronization” option.