Seems like the TSA is damned if they do, damned if they don't when it comes to making sure the pax that placed the laptop ito the X-ray is the one who collects it. However, the problem is easily solved.

I hope there are TSO's reading this:

BLR handles lap top theft prevention right: every tray has a unique number, and the pax is handed a tag with that number. When the pax emerges from the WTMD, he hands his tag to the screener, who matches that number with the tray.

If carrying multiple laptops, I suggest putting a common label on them, such as a business card taped to the top. If concerns about ID theft are an issue, use a sharpie to blot out everything but the first name and company logo. That way if one is challenged during collection, one can point to the common label.