What is this? (strange lugnut thing)

[Rust Buster]

Maybe a dumb question... I have this one lugnut on each of the front wheels on my 67 WM300. It is reverse thread (which I thought they changed before 67, but I guess I am wrong).
It is female threaded onto the wheel stud, and it has female threads into which a box end male thread is fitted. It sticks out much more than the regular lugs. Was this for an attachment of some sort? Any info is appreciated.
Thanks

[Frank Irons]

Looks like a dually lugnut all rusted together.

Frank

[greg rider]

Exactly what it is. Nothing special. Two are definately rusted together.