Brian & Jim - Thanks for sending me to the T206resource.com - I had actually gone to the website before my post, but didn't find what I was looking for, but just went back again, and found it. A nice spreadsheet with all known examples highlighted. (Again, Terrific work Tim & Jim and contributors! What a nice resource for the collecting community)
Chris - I wonder if the Sid Smith Atlanta from REA Lot was resold in the Goodwin auction individually and that is actually the same card in both auctions? (Both auctions are from 2010) -- Thanks for the 2 links !
http://t206resource.com/Brown%20Old%...Checklist.html
14 Documented Brown Old Mill Backs with 3 being duplicates.
12/13 Documented Ty Cobb Backs (JimB) or 13-15 (Brian)
The Race for Rarity is neck and neck... If the 3 duplicates are not duplicates, then we are down to 11... (How sure are we that there are 3 duplicates?)