Register in rman catalog a client which was already registered

Hello,

I have a new NBU domain, and I'm currently in the process of moving some clients from "old" domain to this new one.

When I try to register oracle clients with rman catalog on the new domain, Netbackup is complaining that the client is not registered in the rman catalog.

 But when registering the same client in the "old" (ie current) domain, there is no issue

I believe it's because when we first registered the client, it was configured with the current domain, and now it doesn't want to register it with the new domain because we can't register it twice.

But DBAs are saying that we can't unregister the server from the rman catalog because they will lose their backups.

Is there a way to register the client on the new domain ?