if a male member and a female member are both posting from the same IP address, they better be willing to provide proof that they are not the same person when asked (and they should be asked). the reason i don't say banishment right away is because there are a few legit situations like that.
an alter created solely to stir up trouble by flaming people or just posting total BS should exposed immediately, possibly in a locked sticky at the top of the forum where they've "done their damage." the creator of the alter, however, that's a tough call. non-plats who create an alter, IMO, should be banned unless they go plat and stay plat. plat members should get one warning, unless the alter was in violation of the TOS for EF or really over the edge with maybe racism or something that won't be tolerated from anyone on the site anyway.
funny alters should be allowed to stay, but with their user title changed to say who's alter they are, unless someone decides to blow the right person to keep it a secret. but in the case of SH$DOW F$LCON, who has plat "alters" that he openly admits are his, then let it be.
all that is just my opinion.