The biggest difference is the timing of the standard target discrimination check (see [FAQ 65-]). Even in previous releases, there was one discrimination value per SCL. At adjudication, each stick did a random draw relative to that value in determining whether each stick will be assigned to the most valuable remaining standard target. Now, the same check is done, but simply drawn earlier to be able to decide which munitions are used for WMD v. non-WMD.
The reason they are instrumented on separate lines is because of when the discrimination check was done.