This approach isn't recommended. We recommend implementing multiple commands in order to start different modules/roles of your package but to build and distribute this codebase as a single package.
If you still need to build two or more Carbon packages from the same codebase, you have such a possibility. As I described at Package config, Carbon config has to be located in the root of a codebase, but carbon build has a parameter -c/--config which defines a path to a package config. Thus you may have multiple package configs with different names in the root of your codebase and use them for building of multiple Carbon packages.