Any gancho can be a double-gancho.
The Mark transfers his weight to the back leg, and uses the power of the co-contraction for the Revel’s voleo to enter a voleo himself.
The partners support one another by intensifying the arch of connection with hip flexion, co-contraction of the base legs and intensified triceps contraction.
It’s easiest to enter a double gancho from parada. Remember that any sacada can become a parada.
The most advanced double-gancho is marked as a pro voleo linear.