I use Google Calendar, Contacts, and G-mail exclusively. Before I received my phone I input many of my contact's birthdays into Google Contacts (through G-mail). I then enabled the Contact birthday calendar through Google Calendar so that all of my contact birthdays should show up in my GCal. Then, when I got the phone, I synced my contacts with Facebook for HTC Sense, which synced birthdays, phone numbers, etc. After doing this, all of the people's birthdays whose birthday I had already entered, showed up twice in my calendar. I do not have the Facebook calendar enabled on my calendar app, so I know that this is not causing the doubling. It seems to be ignoring the fact that I already entered the birthday, and adding a second birthday, thus making two birthday entries in my calendar. My friend has an HTC Incredible and it is doing the same thing. Anyone else have this problem... or, figure out a solution?