@CarbonBee Did I understand correctly that the DNS of cloudron A and Cloudron B are different above?
If so, the behavior is expected (not saying it is correct or even good). Currently, there is no easy way to easily 'migrate' domains - it is only easy to migrate a Cloudron from one server to another provided that all the DNS remains the same.
Can you explain your use case a bit more so we can try to come up with a solution together? I guess you are trying to test your backups? How can we make this work when Cloudron has multiple domains? Once you restore to another server, Cloudron will do the DNS setup of apps automatically and it will end up re-configuring the DNS of the apps to point to this new server.