FULL REQUEST:
API=RateV2&XML=FIRST CLASS921019201001REGULARFIRST CLASS921019201001REGULARFIRST CLASS921019201001REGULAR
FULL RESPONSE:
921019201001REGULAR1First-Class Mail1.22921019201001REGULAR1First-Class Mail1.22921019201001REGULAR1First-Class Mail1.22
So it looks like it is only sending a request for 3 packages, not 5. I'll open a support ticket as you suggested. Thanks.