I think this section of the documentation on the Incremental Response node might help to explain how the scores are calculated for the 2 approaches (using a combined model, or separate models for treatment vs. control):
https://go.documentation.sas.com/?docsetId=emex&docsetTarget=p002lnittq9wd5n1cf0ujrccc0hv.htm&docsetVersion=14.2&locale=en#n0dxc9jia326f9n1a0owv7gb6cjx
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