Technically not really duplication in the strictest sense, but this bug allows the player to convert any item into any other item, provided they have at least 1 of the thing they want more of.

This bug only requires AE2 and Storage Drawers

Fill a 1x2 or 2x2 storage drawer with a large amount of any item in any slot except the first slot. Let's call this item 1. I used stone.
Attach an import bus to that drawer and set it to blacklist only item 1 and fill it with acceleration cards.
Hook the network up to some type of storage so the import bus will actually pull items. I used a second drawer.
Place 1 item that you want more of in a drawer slot before that of item 1.

The minimum condition for this to work seems to me that the import bus attempts to pull more of item 2 than is in the drawer and starts pulling item count from item 1 instead, resulting in the creation of more item 2.

I have provided some pictures to help. In this set of pictures, I placed a single diamond block in the top left slot of the 2x2 drawer and it imported 96 diamond blocks into the 1x1 drawer while decreasing the quantity of stone by 95.

Crash Report: https://pastebin.com/HQKif1Tv

The corresponding issue in the AE2 tracker is AppliedEnergistics/Applied-Energistics-2#8592

We were visited by an AI bot yesterday that provided an analysis of the problem from both sides, maybe this can help you a bit. I‘m not sure however if the suggestion of not applying the slot reordering has any side-effects, but maybe it is a starting point for further investigation.