I do believe the original 'seals' were made of a tar-like material. You may have seen some in old trucks that have been baking in the sun for decades where the tar just kinda melts and runs down the bezel. I would guess one seal goes behind the glass (probably the thicker one) and one goes in front of it to insulated it from the steel retaining ring/bezel do-dad.

1950 4100 - unrestored and driven weekly for almost no reason at all.