The problem is the way they duped caused these items are invalid under the hood, the items ended up sharing child objects in a way the code was never designed to handle. We will be dealing with server instability and very strange behaviors. As an example some of the weapons they cloned had ADK on it and if they made 5 dupes there would only be one single ADK, as soon as someone deleted the weapon they would get the ADK deed and the other weapons would be in an invalid state. It’s not safe to keep these invalid items on the server.
Also, deleting the banned accounts items first will not change the fact that an item was duped! It either was duped it wasn’t and it being on a banned account had nothing to do with it.
And you are not correct in your logic, there is no way the “sister” items are 100% legit, we can not prove it with the data we have and we know for a fact they duped many things that people “loaned” them and did not return the original to the person who loaned it to them.