On the current version for 1.18.1 ([SimpleBackpack_Fabric-1.18.1-1.2.31.jar] There's an issue that allows players to easily dupe items by using 2 backpacks. Add me on Discord ItsYoBoi#1111 and I'll show you how to replicate. I do not want people to mass dupe on servers if I show the method.

I have witnessed this dupe on multiple servers as well as in single player. Please consider patching this with a hotfix ASAP. We have multiple servers running this now on 1.18.1. Thanks in advance!

come to my discord channel, then DM me. I don't send friend requests due to scams

This is difficult to test since I cannot replicate.

Can you try this test version? there is a test backpack (the red one). Can you test for dupping please?

SimpleBackpack_Fabric-1.18.1-1.2.31b.jar.zip

Any update on this? Hoping to hotfix this if possible on 1.18.1

Yes. I understand what is happening, my slow computer and 55 year old dexterity don't allow me to replicate it.

Was @Xano11 able to demo the exploit to you at least to see the way it worked? I'm hoping that they can test with this file as I have not heard back from them yet.

Can you test the .31b version red backpack to see if you can dup items please?

I suspect the error crept in because of my use of the older fabric container api. I am overdue for a complete re-write of the backpack logic. in the meantime, I think I have a solution to prevent the dup issue.

I can't get it to do it with .31b but want to get @Xano11 to try as they could do it easily.

Closing this issue since it is related to previously opened issue.