Depending on the size of your services/components (number of methods), I would rather try to split them into logical units rather than based on the number of computers you want to connect.
For example, it can make sense to have two different services implemented by the same server: One for internal purposes and one that is to be published. Or a service is split into two parts, because these two parts do not really belong together logically, although they are for some reason implemented by the same component. All of these services may or may not share the same IDL file.
Last not least, if you still want to minimize the amount of files, keep in mind that declaring, publishing and knowing about a certain service interface does not imply, that a given component must implement the service, must be able to reach the service, wants to use the service, or is allowed to call it.