Vintage BMW Motorcycle Owners

Can anyone identify this seat mount on a '65 R60? A strange, twin spring affair.
Brian

I think that is a passenger seat converted for use as a driver's seat. Is it by Pagusa? Duane shows a picture here:

https://www.w6rec.com/duane/bmw/seats/rackseat.jpg

I have a passenger Pagusa seat (rack mount) that came with my single cylinder bike...it looks very similar to yours and to Duane's.

Kurt, this is on a bike that’s for sale on EBay. The saddle has Pagusa rubber. I can’t see from photos how it’s mounted or what modifications were done to the seat frame and/or bike frame to do this. And WHY do this on a restoration?! Otherwise looks to be very nice.
Brian