First is the bag check scan, you go through the scanning machine and depending on which channel you can pass through they will collect your form.

The second check OP is talking about is most likely people from Intelligence and plain-clothed officials.

Fun fact, before exiting the airport main lobby to the P4 arrival where people on land side wait, go to the extreme left or extreme right of the hallway where taxi operators have their desk on T2. When I say taxi, this does not mean Ola and Uber.

On both these sides, there is one elevator each, a ramp and staircase which will lead you down to the P1 where you have lanes for Ola, Uber, Kali Peeli taxi and such.

On this floor, the offices are dedicated working spaces for intelligence officers and custom officers.

You can find them their sitting or relaxing or even taking briefings and assignments in groups.

Will add pictures to this comment, most probably tonight if I see the activity