I think there is a bit of confusion so I have attached another screen shot to show what is happening.
Using a new active style to make the AS dimensions called "DSC_DIM_STYLE1_DUAL", I set the "Placement" to "Below primary value" then created the AS dimension as shown in the attached JPG. The Alternate Dimension appeared after the primary dimension instead of below, like I had chosen. I then created a ACAD dimension using the same active style ("DSC_DIM_STYLE1_DUAL") and the alternate dimension appeared in the correct location below the primary dimension. The option to pick the "Below primary value" only seems to work with ACAD dimensions and not with AS dimensions.