You did what you had to do... It's up to the signature campaign manager to remove them from the campaign or not. I don't think it has anything to do with your DT "power" or something along those lines.
Yes, as you said should have nothing to do with my DT power. Managers have the right to decide anything, but when they make written rules, it can be a bit unprofessional if they break them, unless they remove them from the rules.
Maybe the second rules is limited to the use of alts in the Stake campaign only.
How not, even though only one account is accepted and is in the campaign, this user wants to cheat the campaign by registering with two accounts. Don't you think it's cheating?
I've also notified the manager about the tags I gave to both accounts, now I'm waiting to see what the manager will do for them or at least one of the accounts still in the campaign. If managers don't want to hire spammers or users who break the rules, then they shouldn't hire cheaters either.