Each walking cycle has two periods of double support (DS), as shown by

Gait cycle: phases, muscles and joints involved.

Amy J Bastian's research works Kennedy Krieger Institute (KKI) and other places

Parkinsonian gait - Wikipedia

Amy J Bastian's research works Kennedy Krieger Institute (KKI) and other places

Gait Cycle - an overview

Dynamic postural stability results in the groups

Each walking cycle has two periods of double support (DS), as shown by

Full article: Intramuscular Coherence of the Lower Flexor Muscles during Robotic Ankle-Assisted Gait

The Gait Cycle - Physiopedia

Inter-limb weight transfer strategy during walking after unilateral transfemoral amputation