For a recent project, I was trying to trigger the same state from the Any State in the Mecanim Animator in Unity. When doing so, the transition did trigger, but it failed to flag the trigger back to “false”. This was causing some animation bugs, since the game was setup so the user can replay that level. Upon replay, the animation would get triggered twice or since the trigger was still flagged “true” before it could reset back to the original state. To fix this problem, there’s a check box called “Can Transition To Self” in the inspector which you need to turn on (it’s unchecked by default). Check it and you’re done!
unity-animator-trigger
Source: http://answers.unity3d.com/questions/877897/trigger-the-same-state-again.html