really, I never had an issue with having people play multiple chars in rp's I GM
and just for the record, I have quite the experience with playing multiple char's my self, but I admit it depends on how far the char is worked out, Neo his personality is not fully worked out, but then again Pink-spider is and I know for a fact she is different from Neo by a lot XD

well I dont want Neo to die... so... maybe I dont know would it be allowed that I switch between them at times, that for some reasons Neo has to return to his world and Pink shows up and then Pink has to return to her world and Neo shows up

would that much be allowed?
if so, then the switch will be done each time they return to the negetive zone, that way I wont play 2 and can still use both
only the little moment between the switch can they be in the negative zone at the same time but that would be in one post only to post the switch between worlds