First off the Center is .999 Silver. What you have is a strike somebody has altered, they punched out the center of the Rivera strike and inserted it into the Brass Collar of the other one. The Rivera strike would have had .999 silver on the Rim and the Hilton strikes all had the .999 on the silver center.
It is worth Melt value, hope you didn't pay a lot of it. Where did you come across it?
Walt