Mag Plug gasket

My 914 has a black plastic gasket/washer as shown in the picture.   Recently inspected and it looked really good (no metal), however when I reinstalled and torqued to the specifiec 18.5 ft lbs,  I felt like I was crushing the black gasket/washer.

My question -  Does anyone else have this black plastic washer?  should it be there?   (This washer had to be factory supplied or installed as I am only owner and engine only has 70 hrs on it. )

If the answer is yes,  commonly installed by factory,  what is the part number so I can order a spare?