This is a great ball handling drill to use to warm up before a workout or practice. It will help the player work on their ball handling, and also help them get warmed up and ready to go full speed. The great thing about two ball basketball dribbling drills is that it takes away the option of being able to switch the basketball over to the strong hand. A lot of times when a player gets uncomfortable they will immediately switch the basketball over to their strong hand, which hurts the development of their off hand.
With two basketballs though, that is not an option. Two ball drills also maximize time by allowing the player to work on both hands at the same time. If you have limited gym time this can be really important. Also, dribbling two basketballs at the same time really helps to add more difficulty to the drill.