You misunderstood. Essentially every INF needs a unique name. When constructing the OS and all first party INFs, this can be enforced at build time. For dynamically added third party INFs, it is the wild west in terms of file naming and INF names can easily conflict between two disparate companies (and if the package was copied from a sample, highly likely). So, each third party INF gets its own unique OEMXxxx.inf file name. The key here is successful import of the driver package.