I have heard of some people taking antipsychotics PRN. But I don't think that they are PRN for psychosis.

It's not unheard of for people to be taking more than one antipsychotic. I am currently taking two right now as well. But I'd say if you think that two may be too many you can always talk to your pdoc. I think when people take two it is because one antipsychotic may be working well for psychosis, while another may be working well for other symptoms. Or, one may work for psychosis but side effects are too bad at a high dose, so adding another antipsychotic to help the one at a low dose seems to work.