0. ALWAYS PROVIDE INFORMATION ABOUT MODLOADER (Fabric / Forge) AND MOD VERSION (For Example 1.19.2-8.2.10)
   travelersbackpack-neoforge-1.21.1-10.1.6

1. Describe the bug
   The backpacks will be shown twice in the EMI, and backpack icons are all with tank
   Versions below travelersbackpack-neoforge-1.21.1-10.1.3 do not have this issue

2. Write steps to reproduce the bug
   pass

3. What is expected behaviour
   pass

4. Screenshots (If applicable)
   

Backpacks will always display with tanks in creative menu, that's how backpacks always looked so I wanted to keep it. Backpack being shown twice is in fact a bug and I will check that

Basically, the duplicated backpacks are backpacks with different component data. I use special method to add backpacks to creative tab with additional data, but emi shows both - registered items and items from creative tab. That's why its "duplicated". Unfortunately no way to fix it.

So it maybe a EMI issue?
I will seek help from emi

That's the explanation I've read on same issue but reported to emi dev. But sure you can ask if there's any solution now.