We have, 13 times at least. Sadly he is not dumb enough to not know how to bypass that.
Dang. At this point yelling at sonicsucks' ISP or VPN might be the only option, so that they can yell at him for us. That seems to be a thing in Japanese BBS like 2ch/5ch apparently.
At this point, I wouldn't be surprised if the mods have their own checklist with: 'ban that sonic20 guy's alt account again,' written on it as a weekly task.
Why anyone would go to such lengths to act in such an irrational and bizarre manner, escapes me.