That's very true that those who are banned should not be given the second chances when it comes to palagrism or ban evasion. Of Course most to the accounts are banned on the basis of palagrism and Ban Evasion is just that that particular person/account that was banned had other accounts too and they should be banned too because the person behind them is the same who was involved in doing palagrism. If he can do palagrism from one account, he would probabaly be doing it from other accounts too.

Usually the person doing the palagrism know that he is cheating the system by copy pasting the post and avoding the effort required to do the posting. Even if there a few cases where the author wasn't aware of the consequences of the palagrism, there is no way to judge if he he didn't know about it or if he was doing it intentionally.