Modpack version
0.4.1

Describe the bug
Disenchanting Tetra tool with Pneumaticcraft's pressure chamber under vacuum yields book with one of the enchants and tool with all of the enchants still applied, when one of the enchantments should be erased.

Can you test if you can get more than one book per enchantment on the tool?

IIRC Tetra manages enchantments differently on their tools.
If you try enchant using the enchant command it'll appear to not work when the enchantment is really there.

Similarly, when you disenchant a Tetra tool it appears to have not removed the enchantment visually, but it has actually been removed.

See Lothrazar/Cyclic#1737 (comment) or search "enchant" in the Tetra issue tracker.

I suppose the most that can be done is ask mods that add disenchanting mechanics for a config or tag to filter out items from disenchanting.