Yes. I know. That’s what I wrote before: the label must be unique within a product. The GUI seems to enforce the same for the name, too. Although, looking into the database at katello_root_repositories.name that can even be null which is weird…
Either way, the correct selection for the module (and in the GUI for that matter in Host - Operating Systems settings are reset/missing when editing and ambiguity) in a host group depends on the operating system which should nail down to the product thus identifying potential repos.