Describe the bug
Crafting Grid upgrade appears to dupe items.

Was able to recreate for myself in..

• Single Player on Survival Mode with cheats disabled
• Multiplayer on Survival Mode without OP

Reproduce Steps

• Place item in backpacks crafting grid.
• Click result (Do not shift click, that works)
• Items should be in hand and a copy should of fell to the floor.

Versions
sophisticatedbackpacks 1.16.5
3.15.18.698

It appears it was caused due to a conflict with the mod FastWorkbench Minus Replacement.

yeah that mod is bugged, just use a regular fastworkbench and you're good.