i agree about the facetwin thing, but if the person is willing to not go that route and avoid the comparison/facetwin aspect, it shouldn't be an issue. it's the same to me as someone playing different roles from the same actor. i'm not a fan of the facetwin angle, so even with multiple chars from the same actor, i prefer to not play in to the 'i thought you were my boyfriend/brother/dad' game.

someone pushing into a cast from an oc or from any other cast is a bad move. having sameface doesn't make it better or worse. just still bad.