Today the Backend configuration file format has room for exactly one database configuration, one zm-rpcapi configuration and one zm-testagent configuration. If you need multiple zm-rpcapi configurations, you need to have multiple Backend configuration files. This means the database configuration would be duplicated across multiple files.

The Backend configuration file format should be updated to allow for multiple zm-rpcapi configurations in the same file. Also zonemaster_backend_rpcapi.psgi should let users choose which zm-rpcapi configuration to use by setting an environment variable.

N.B. This feature would come in handy for use cases like what's suggested in #1119 (comment).