Modpack version
1.76a

Issue
Amber from both BoP and Thaumcraft generate in the world. I suggest disabling BoP's, because it doesn't drop Preserved Curiosities, and then maybe increasing Thaumcraft's to compensate for the difference.

Also, apparently BoP's Amber is hidden in JEI? It's a bit weird that BoP's spawn more (at least in my experience. According to JER, Amber Bearing Stone is more common, which isn't what I've observed).

I'd love to, but I don't know how to disable BoP ores to be honest.

They only spawn in specific biomes, that's most likely why the Thaumcraft Amber has higher generation in JER.

lol I looked it up and found this

Guess there's no way, which is very odd

I believe disabling them is for all BOP gem spawns.

Could you disable them by default and then add custom ore spawn JSON files using COFH World and then just omit re-adding the BOP Amber Ore to worldgen?

Could work but it may be more convoluted a solution than needs to be.

There is one way of doing it by default, but that will override all other generator-settings used, which I think is worse than having duplicate ores :/
https://biomesoplenty.fandom.com/wiki/Configuration

Biomes O' Plenty Wiki

Configuration

NOTE: This wiki is not supported or endorsed by the developers! Information found here may be inaccurate/outdated, and should not be used as reference for issues, bug reports, or any other requests to the developers! This page documents the various functions of the Biomes O' Plenty configuration files as of BOP version 2.1.0.X. The files are listed in alphabetic or zip files