WTF!? That is like YMMV (multiples) on top of YMMV (crazy overrides for no reason).
Promo 14143 is not the bonus value promo - at least it wasn't a few days ago. My receipts have 14181.
But yeah, the 10% PUR applied to the base value + the override amount. That much is clear. For example, NFS:MW must have had a base of $17. Add an override of $18 to make it $35, then you get the PUR 10% for $3.50. And then promo 14143 for another $17.50. Unreal.