Although you have had your problems in the past on the server, I believe that when you came back from your break you were a better player in most cases up until the duping. The duping, however, was a very serious offence against the server, not just because it provided you with an unfair advantage but also because you didn't report it to staff and instead continued, repeatedly, to use it, knowing that it was wrong and unintended. You already had previous warnings about harassment and spam in the past, and still thought that it would be okay for you to do the duping. I don't believe for a second that you were purposely trying to get banned, despite the messages that you have sent me in my DMs in the past, which I will refrain from posting publicly. This is often just used by players who are trying to excuse their bad behavior.
In short, I have seen you make progress in the past to become a better player and follow the rules, but until you can give us an honest, truthful and in-depth explanation as to why you cheated and why we should unban you, my answer is no. I would recommend starting a new thread and following the appeal guidelines as well, as that is a great start to showing you care about the server and its rules.