fuel petcock seal questions

Hey guys, I bought a new fuel petcock lever and a new rubber seal for my 660 because the screw that sits inside holding the petcock to the assembly rusted; which meant I couldn’t remove the petcock lever alone, I had to take of the fuel dial thingy (the metal piece that says ON OFF RES). As I removed the dial, I noticed that the sealing ring that sits in the assembly was metal. is it supposed to be metal? Because the seal ring I received in the mail was rubber. Huh. For now I have put both in because the metal one was slightly smaller than the rubber one so it looked like it was meant to be there. any comments are appreciated