The HTC Mail memory leak and Facebook contact duplication issue are completely separate and unrelated issues. People have been experiencing the HTC Mail memory leak long before the recent Facebook update, and people (like myself) have experienced the Facebook contact duplication issue and have never even so much as opened HTC Mail.
Symptoms of the Facebook issue include:
-Multiple listings of the same facebook contact in your address book
-Unusually poor battery life
-Phone that is warm to the touch
-"Low storage" notification, despite plenty of free storage space on the phone
-Constant "sync" icon in the notification bar
-Completely unresponsive People and dialer apps
To resolve the Facebook issue without doing a factory reset:
1. Back up any "phone" contacts that you may have to your Google account or a separate file.
2. Search for "Facebook for Android" in the market, go to the page, and hit the "uninstall updates" button (there may be other methods of uninstalling, this is the one that I used). DO NOT reinstall any updates to Facebook until we have confirmation that Facebook has resolved this issue.
3. From the home screen, hit Menu, Settings, Accounts & sync, and ensure that Facebook is not on the list (Facebook for HTC Sense is ok). If Facebook is on the list, click it and hit "Remove account".
4. From the home screen, hit Menu, Settings, Applications, Manage Applications, Contacts Storage, Clear data.
5. Restart your phone. Your facebook and google contacts should automatically resync, if not, you can queue a manual resync from Accounts and sync in the settings menu. If you exported your phone contacts to a file, you can reimport them at this time.