I found this one a few weeks ago. As I read, 2 over 1 is usually found with large 9 variety. But this one is a small 9. Someone have documentation about this one or have ever seen this? Thank you very much.
Highly unlikely 2/1, but not impossible. 1891 small 9's are all 21 leaf reverses. 1891 large 9's are all 22 leaf reverses. All 1892's are 22 leaf. Start from there and you'll see why it is extremely unlikely.
"Dipping" is not considered cleaning... -from PCGS website