Diablo 2 1.13 working dupe Closed Bnet

I need a working Diablo II duping method for Closed Battle Net 1.13. It should be unpatchable, or at least last a quite long time. And not too complicated. I can use multiple D2 windows if needed. I first want a proof that it works before payment. Diablo 2 is a game mostly played online on Battle Net and duping is a secret way to duplicate items you find in the game.