No problem. I saw the solution to this in an episode of Star Trek once.
First, we rely on an omnipotent being who is obsessed with Thayos (basically, Filth) to send his consciousness forward in time to his older self where he could convince his then ex-wife to dig up the remains of the Zam site so he could blast Duo with a tachyon beam. This will have the effect of making Duo even more inglorious and grossly incandescent in the present, outshining all trolls in the site, so Thayos should blast Duo with a tachyon beam in the present. Next, Filth will send Thayos back in time to his younger self where he'll discover that Duo is an untouchable admin trolling Zam-goers for sport and blast him with a tachyon beam there as well.
Ultimately, Filth will sweep Thayos to a time in the past when Zam was owned by gil sellers, and instead of shedding their evil masters, Duo, as the owner and operator, will use his powers to hack everyone's FFXI accounts and destroy both the forum and FFXI in the process.
Shocked that Duo is getting worse and worse in the past to become such a destructive force, and realizing that all those tachyon beams he used on Duo was what caused him to gain these powers in the first place (thanks for nothing, Filth), Thayos realizes his only course of action is to allow himself to be eaten by Duo in all three time periods.
So, that's all you have to do to restore the timeline. Good luck!