There is no rubber seal in between. Just the fabric strip against the doorcard.
it is a very strong discolouring. Almost looks as if it has been redyed in tan in the past without removing the armrest etc. I have seen a few interior colours from partly dsimantled Deauvilles and Longchamps and the diffrence in colour was marginal, far less than instance the mousehair dashtops which far more prone to fading.
The leather dyeing back then was still nitro cellulose based an far more durable than the current water based.
I know it came with brown leather from the factory but there is only one that I know which is called Testa di Moro. That is a dark bitter chocolate colour.
Who knows, maybe they had a medium brown option also.