Most, if not all, the applicants have applied to more than one airline in the region. They assume you have and if they want you they will try and get you before the other one does.
When I came out for my interview I was scheduled for Emirates and Etisalat, Qatar being a choice if neither of the others offered me a job.
After completing my AUH interview and was accepted I called EK and told them that I had already accepted a position and would not be attending their selection. Both companies were first choice options, I just did not wish to expose myself to the stress of going through the process a second time. So far have had no regrets with my choice.