I got confused with this too and very very worried when I didn't see my shop that I had completed that cost me 50 bucks!!!!
So I emailed an inquiry(Don't be afraid to do this, it saves ALOT of misunderstandings!)
Anyway, KSS schedules shops for over 60 different companies that use mystery shoppers. I have found some duplicates, but not many (shops listed with the companies I am signed up for).
another note is that even though you sign up with KSS, you actually put the report in at the original company, and that company also pays you, not KSS. that is why you have to sign up with the actual company if you are not already signed up. That is ok though as you will get signed up at companies you haven't signed up for and get more shop offers...
You must remember to go back to KSS and put a confirmation number in that you completed the shop.
So what I do is make a sub-accounts receiveable to KSS for any shops I do through them and note they are a KSS shop.
That is my information from KSS...