Currency duplication altar bug

Hi,

I had Eldritch Altar giving "X% chance to duplicate currency from slain enemy" combined with Altar giving "Map Boss will drop 6 Divine Orbs" resulting in 12 Divine expected, but only 10 dropped. At first I thought this was a stack size limit, but that would be 20 for Divine Orbs.

SSF Standard
Tier 16 Iceberg
I have cars from another map scried (Spelling?) on the Iceberg