We have a lot of 2 vintage 2 way screw in light sockets by Eagle.  I believe the plastic portion is Bakelite and the tops are brass.  1 is a bit discolored on one side.  I have not tried to use these so do not know if they actually work.  There is a bit of wear showing on them. 

2 Light Sockets Vintage Bakelite 2 way screw in