I recall the first time I saw a coach swinging two gymnasts on the same straps Bar. I instantly tried to hire her. 🙂
It was the only way her kids could get enough repetitions, she told me. (Most gyms do not have enough strap bars.)
Since then I’ve seen it many times.
But I was surprised and shocked seeing a coach at Manjak’s put 3 kids on simultaneously. 🙂
They were working kip drills.
Gymnastics Coaching.com 