You how the close AM coins keep being thought of as wide AM's because they have more space than normal between the A and M because of die polishing? Well the same thing could cause the 1 of a near date SBA to be further away from the rim than normal, but not as far as on a narrow rim coin.
Two for one sent from mint, set should have contained 2 SBA and it contained 3, with two in one space as shown.
Looks like a proof. ALL 1979 proof SBA's are narrow rim. The wide rim is ONLY late-in-the-year business strikes.
Thanks Mr Bellman, my father in-law left many SBA coins to me, and you are right it is in a proof set..good eye.. The other photos are from a Uncirculated set with P&D mint marks the doubled coins are SBA P mint marks both in the same pocket error but not considered a mint error as I have been told.