Your score is the total of repetitions on both of the 2 movements. There is no break between the 2 movements.
Your score will be optimal if you manage to hold with a continuous and regular intensity over all 4min.
TIPS AND STRATEGY
Go on a safe and effective pace on the 1st part to avoid taking unnecessary risks if you rush. The slightest mistake will cost you a lot of reps!
Improve your Double-Under: video