The DXB lanes are different - there is no systematic shortage of bins. So while you do have to place carry-on suitcases in their bins, the lane design does not limit you to only placing one bin in at a time.

This is unlike the Newark system, where you have to keep waiting until you get a bin, you can only take one bin at a time, and then you have to wait again to simply push your bin onto the conveyor belt.