How are dumbbell exercises counted?

On iOS, you have the option to adjust how you would like your dumbbell exercises to be counted. If you go to the Profile tab > Settings > Bonus Options, you will find a Count Dumbbells Twice option. If you enable it, it will calculate the total volume for a workout, as well as the volume charts for that exercise. If you disable it, volume will not automatically be doubled.

On Android, weight for all dumbbell exercises is automatically doubled.