I’m not sure if it was Blackberry, Android, or Facebook, but something caused all the birthday events in my Google Calendar to have 36 duplicate entries each. This not only caused visual pollution but also resulted in me getting 36 notifications on my phone for every birthday.
The first two apps I tried that promised the remove duplicates didn’t, so I nearly decided to write a duplicate remover myself. However, the third app I tried — GCalToolkit — worked. I used its free trial mode to purge all of the duplicates, and my calendar is clean again.
Incidentally, I ended up signing up for Google’s 2-step authentication, as one of the non-functioning apps was password-based rather than OAuth-based. I was unwilling to give it my actual password, so I used Google’s application-specific passwords feature which depends on 2-step authentication. I’m still somewhat apprehensive about being able to access my email should I be travelling or should I lose my phone.