Is it necessary to change IP?

If I were to have multiple AC accounts, is it necessary to change IPs every account? Do they log it and will I be banned if I log in to two or more AC accounts with the same IP?

Thanks for the help.

1 IP per account would be good!

Yes, Sample is very right. You should use one IP for one account. Though AC is not that strict right now about this issue but who knows. They cleared their intentions after introducing verification process so better be cautious to avoid any complications.