When more than 100% chance of a drop it's by default a half the chance of a double drop.
I'm guessing this mod changes it so it's a 100% of 1 drop and the rest of the chance for a extra drop.
Example: 1.5 red geodes from washing, normally 75% chance of double drop, after mod 50% of extra drop.
Doesn't change anything in the long run, but helps with expectations and the law of small numbers.