Scarab not working or wrong text

Harvest scarab of doubling, says "Lifeforce dropped by harvest monsters in area IS duplicated"
Either it doesn't work or isn't a guaranteed chance which clearly isn't specified, the wording makes it seem to duplicate all lifeforce dropped.
I've used it multiple times now and it's clearly only sometimes.

Having not messed with the new scarabs yet myself, I assume it works exactly how the sextant modifiers worked.

What the sextant modifiers did was "duplicate" essence by making the monsters drop twice as much in a single stack, so you'd never see them dropping an odd number. This way, it could synergize with the Atlas Passive that "duplicate" essence by making a second stack of equal value drop.