Unfortunately, there is no way to set up the relays to be mutually exclusive. If you can let us know what you are connecting, perhaps there is a way you can use the normally open vs normally closed to accomplish your goals…as in when you send an ON command the normally open side turns off and the normally closed side turns on. Assuming both loads can be powered by the same power supply.
Edit – Should clarify, with the ISY…it’s not really possible. Lee is correct regarding snap shot mode, but you would need to modify the link record (responder link from the ISY’s PLM) in the EZIO4O…which can be done using the SHN Utility Suite.