Since the mystery has been solved I'll just chime in on the Greek use of the double eagle. That was commonly associated with the Byzantine Empire, but in current Greece you find it only on Church flags. A similar symbol was the Phoenix used during the military dictatorship of 1967-74, but that bird had only one head.I'd bet it's Greek. They used the Grease gun post war and someone on another forum thinks they used the double eagle as well