This is something that was bound to happen. I remeber buying a B9 3.5 e28 a very long time ago that did not have the plaque. It had been taken out, the holes were still there but there was no plaque.
I had to send chassis numbers and engine numbers to Sytner before they would give me one. And I had to fax them the log book with my name and address on it before they would ship it. And then they would only ship it to the address on the log book.
But they did check everything and verified my model and engraved it with the correct details, all free of charge.
Most of us will check with Alpina - either Factory or Sytner - the actual chassis numbers before going any further. It may fool those who regularly buy cars with their eyes shut or have no idea what they are buying.