Edit: This bug report appears to be a duplicate of MC-120761

This is affects vanilla creative and survival mode:

Expected result: Recipe should fail

Actual result: Recipe succeeds, deleting the enchanted book and increasing the experience cost

Description: Enchantments can be re-applied to tools that already have that enchantment using an anvil

Steps to recreate:

1. Open world
2. Obtain tool, enchanted book, and anvil
3. Enchant tool in anvil
4. Re-enchant tool in anvil with same enchantment

Proposed solution: Anvil recipe shouldn't craft if it has the enchantments already

I haven't tested every enchantment, but this bug has occurred with the 5 that I've tested. On a data pack world (different than the vanilla one seen in the video) I confirmed that this also extends to custom data driven enchantments.

This bug appears to be related to MC-95555 and MC-200796