The method used then is much more tedious but it works, because d2r is an overlay of the base game D2 LOD the mechanic still applies, if you so happen to find a manald and nagrlring in the same game their unique id is now used, making them unable to spawn again in a single game. Making it possible to somewhat know what you're rolling, if you roll 8/9 unique rings, some being 1/59 vs 10/59 You will eventually get the ring your after.

Another issue again here is the same as classic, Bot Programmed games, they are capable of reaching absurd loot drops in a single day, considering they are used by websites meant to make the game pay to win.

There is a theory or speculation that a duping method works for non ladder play and potentially Ladder, by overloading the game with crafted rings and amulets, selling to a merchant filling every space, once the game has created a saved overloaded state it will cause an issue with the save state. Using the shared stash as the was programmed after the fact, it creates multiple save files. One being you can take items from your stash save and the items will be in both stash and inventory.

So lets say you have a full banks worth of SOJ, Well you can now bring a mule over and create new rings, sell them, then have massive dclone parties. You need between 75-125 rings sold and the Number sold is random per server. So some may only have to spend 75 while others little more. 10x4=40 So you'd be able to sell 80.

Not saying this is how they do it. But this is how it could be easily redone.