On the xray machines, the images do not disappear like they do with the AIT. They stay there until the new incoming bag replaces them, so if one person gets tapped to go to another position, the image of their last bag is still on the screen. See the images on these machines : http://www.astrophysicsinc.com/Screening_Systems_Sub_Cat.php?naviscreen_id=1&red_title=Mail and Small Parcel Checkpoint Security (these are not the ones we use, but they are the same technology) those images on the screen do not just disappear, they move along off screen as the new images come in. ** Edit to add - I have been informed that some of the higher end xray machines actually do operate one image at a time and the screen clears after each item rolls in and out. This is not typical of the types of xrays used in most governmental areas that require them (TSA, courthouses, etc).