I don't think the 2 JJ's are related, set up at different times, I believe very different experiences. (I have not been to both.)
The one on Foulk Rd is on Foulk Rd southbound, just past Silverside Rd and the Sunoco station, next to the sub shop (Pickles and Chips).
Ying's sounds like the old Ying Li (now Kim's massage) on the SE corner of Silverside and Marsh, about 1 mile east of Foulk - different place.