Out of interest do many airports have multiple duty free providers?
I don't pay too much attention anywhere except BKK where most stores appear to be King Power even if they have different store names.
Note sure about duty free, but I think it is the norm these days that at least at the major international airports you have one operator in the background who controls all shops in their category.
They are often not even branded the same like King Power at BKK. As an example from the airport F&B industry: at a mid-sized airport there may be 6-10 F&B outlets in the Departures area: McDonalds, Boost Juice, a local restaurant, a Gloria Jean's cafe, a local cafe, another "healthy burger" joint, and so on... Looks like a lot of choice for the travel (which it truly is) and a healthy competition - which it isn't because most if not all outlets are operated by the same company which takes out franchises for brands like McDonalds and Boost, then adds a few no-name outlets to the mix, and voila! Cairns Domestic is a good example that I know of, most if not all F&B outlets are operated by HMS Host.
Pretty sure it's similar with Duty Free and other retailers.