A first and obvious reason is to do A/B (or A/B/C/etc.) testing, by linking each pop-up shop to a different model.
Second, you can simultaneously run multiple, focused campaigns and keep track of the performance of each.
Another possibility is to have a pop-up shop for each channel you use and e.g. find out which is your most popular channel.
You can even go a step further with some brands, and create a pop-up shop per region or billboard. Imagine you have multiple billboards and you put a separate # code on it. People can talk with the brand, use the hashtag and its associated pop-up shop comes up. You can easily track the performance of each billboard.
Note that hosting multiple pop-up shops is only available for our Bronze, Silver and Gold formulas. Click the link to find out more differences between these plans.