Steps to reproduce:
1. Create a project that prints out OnApplicationPause(bool) calls.
2. Deploy it to Windows Phone 8 device
3. Press lock button
4. Press lock button, slowly slide screen to unlock
5. See printed out messages. Repeating step 2 sometimes will produce last message OnApplicationPause(true), which should not happen if application was unpaused.

Not reproducible since:
Version 4.3.0f3 (7eed886c2a59)
Wed, 06 Nov 2013 21:12:33 GMT

In order to fix this issue, device should be updated to Windows Phone Update 3. Addotional information can be found here: http://www.windowsphone.com/en-us/how-to/wp8/basics/windows-phone-8-update-history