It is not an account that is banned, it is the person who is banned. So regardless of the IP address or the computer that is used, if a person's account is banned then that person cannot post from any of their accounts (the exception being to post in meta in order to appeal)
They are allowed but not if you've been banned from one of the others as it will be ban evasion.
Posting using multiple accounts is allowed , same thing for selling accounts .
But if you gets banned , using any of the other accounts you have is considered as "Ban evasion" and may get all your other accounts banned. simple as that I guess
Oh ok fine, thanks a lot for all of your replies as it made me clear regarding everything now...
@Quickseller,
You know what, I was thinking from a long time to create new accounts and sell them, seeing you and ACCTSeller doing it openly...
Haven't created any yet as still thinking and I also don't have much time to manage 'em...