The npjava*.dll when placed in location that Gecko can discover at runtime, plays 2 purposes:
1) rc file specifies the mimetypes (from current most version to the last supported version in the chain) to that the browser would know the plugin is of the right kind to process and display the content with.
2) hold and build entry points to plugin DLLs for the func table used by mozilla navigator.

However, we do not need multiple npjava*.dll. Only one that enlists all supported mimetypes will do the job.