In ATM7 0.4.32, it is possible to duplicate any stackable item as long as you have 1 stack plus 1. Ex: 65 iron or 17 ender pearls.

When using a backpack from the sophisticated backpacks mod, you can select an item in your inventory and hover over a backpack and right click to drop the item in the backpack. If you right click an item in there while the backpack is full, nothing will go into the backpack. Although, if you have a stackable item such as iron in the backpack with a stack that is not full yet while the rest of the backpacks inventory is taken up, you can duplicate it. All you need to do is have 1-63 iron in the backpack, then simply try to right click anywhere from 2-64 iron into the back pack. It will in turn max the stack of iron in the backpack and not take anything out of your inventory. I have replicated it in these screenshots.




Also, no, I am not abusing this bug. I believe duplication ruins the fun in Minecraft, hence why I am posting this.

Thanks for the report, i've passed this onto the mod Dev to be fixed

Now fixed in the latest update of Sophisticated core, that mod will be updated in the next pack release
https://www.curseforge.com/minecraft/mc-mods/sophisticated-core/files/4019678