Active Calories seems to add both running activity (from FR620) and Vivofit2 activity.
The total calories summery seems way too big as it used to discard the Vivofit2 calories while performing an activity with FR620.
I seem to be having the same problem with my forerunner 92xt. Since the weekend it hasn't been subtracting the activity calorie count, adding something like another 1000+.
All this happened the same time as the sleep recorder started acting up.