When I use darkdoppelganger-9.2.3-1.20.1, I can add drop items to darkdoppelganger by using configurableextramobdrops-1.20.1-3.4.
But in darkdoppelganger-9.3.2-1.20.1, I can't add drop items to darkdoppelganger by using configurableextramobdrops.
Is there any entity ID problem or just mod setting?

I think there was a loot duplication bug where I messed with this. I use kubejs for extra drops in my modpack with doppelgänger mod. I can look at the loot code I added and see what I can do to allow that mod to work again for you