Steps to reproduce the duplication bug:

1. Open backpack
2. Open crafting menu in backpack
3. Arrange the recipe for upgrading a backpack in the backpack crafting menu
4. Click a recipe in jei to look at
5. Exit viewing the recipe
6. The backpack in the crafting menu get's kicked out into the player inventory
7. Click on the crafting results which have no backpack in the crafting grid
8. Done

I didn't expect the backpack to get kicked out of the crafting grid without updating the crafting results

Mod version
3.20.5.1044
JEI version
15.3.0.4
Forge version (1.20.1)
47.2.32

(Disclaimer: im not very good at this, i stumbled upon this bug and wanted to report it)

If i need to get a screen capture i can

Did a few more tests and it is only a visual bug

Update it seems like a visual bug cause I just tried to click on the original backpack and it vanished