To reproduce this issue:

1. Open the attached project
2. Add 'Test' script on the 'MainCamera'
3. 'Test' script logs in the console when playBackState changes
4. Play the scene
5.Notice that when clicking PLAY it will raise 2 events:
5.1 isPlaying=false, paused=false
-followed by
5.2 isPlaying=true, paused=false

6. When stopping , same thing, only reversed:
6.1 isPlaying=true, paused=false
-followed by
6.2 isPlaying=false, paused=false.

The first event in each case is not needed! Events should be raised in case of state transitions.

Captured repro: http://screencast.com/t/7BIeiKGwv