The lower number in the configuration file is the probability to spawn the fake ores when you break a original block ore.
7 is the default value. If the prob is under 7, Fake Ores will be more present. Unless you set a high number.
It only works on Fake Ores mobs.
Just look at the source code here : https://github.com/elias54/Fake-Ores-2/blob/master/src/main/java/fr/elias/common/BlockDropEvent.java