That's a really old thread to be posting today. lol. The guy is clearly spamming to increase post count. Anyway, like Quickseller said, it's allowed. What is not is to use both account to join in the same camapign, at the same time. You'll be in trouble because that's an abuse and against campaign rules.
Agreed that having two accounts is allowed and is not a basis for you to get banned but the basis for you to get a ban in the forum is violating the forum rules like spamming which these accounts used to abus signature campaigns are characterized by this.
Regarding the 2 accounts if it is joined in the same signature campaign which they don't allow having multiple accounts to join since it is considered as an abuse, it will ban you in the campaign and no payment but not ban in the forum though there's a possibility that you'll be painted red that is if the campaign manager is active in combatting this kind of people.