As far as I know, a certified nursing assistant in one state may apply for certification by endorsement or reciprocity in another state. If the application is accepted and all the endorsement criteria are met then you may hold a CNA license in more than one state. Keep in mind that you need to maintain your active status on multiple registries. This means you need to meet the renewal requirements for each state where you are certified. You can always call the Nurse Aide Registries of both states and make sure this is the case before you apply but I don't see a reason why they would have an objection to this.