Nice Note!  Holder looks blue. A lot of mine are that way... Should be a FREE Exchange for NEW Holders...

I couldn't tell you about back plates, but that is a seriously excellent score. What are the odds of finding consecutive notes graded the same at different shops? That is awesome. Keep them together forever!

yes, these notes will be together for awhile.  What I really want is the SN 5225 note.  Then I'd have 3 consecutive notes and the 5225 is a 4-digit radar!  I suspect the odds are against me there.  

I think the blue hue is from my scanner.  The holders are in quite good shape, so I suspect I rescued them from the show circuit early before the holders received much wear.  What do you think of the grades?  SN 5227 is nicer in my opinion.

I'm still hoping the original owner sees my post.  Anyway, I appreciate the comments!!

I've learned that the BEP printed the backs in quantity awaiting orders from banks.  In this case, Salem ordered sheets of $10 $10 $10 $20 and likely there was a supply of backs probably printed at least 8 notes and maybe 16 notes (so for 16 notes, 4 would be $20s and thus 4 possible back plate (bp) numbers).  When printing Salem 43's order which including SN's 5226 and 7, the backs selected happened to have different bp numbers.  They could have had the same bp numbers and depending on how sheets were cut and stacked maybe it's more likely they should have had the same bp numbers, but not really an oddity that they do not.  An alternative would be the notes were from two different orders from Salem, but I don't think that's very likely (actually, not possible since the treasury SNs are also sequential).  Now, if you come across the $10s with SN 5226 and 5227, they better not have the same bp numbers (if they have the same front plate that is).

Going through my new National Bank Notes 6th Edition by Kelly and here's why we have plain backs with different Fr. numbers (yet same denomination) for some charters.  Acts of July 12, 1882 and April 12, 1902 extended charters for existing banks for another 20 years.  Salem 43 had to liquidate in 1882 because their charter was about to expire and because congress was a bit late and didn't pass a new act until July.  Thus Salem obtained a new charter, 2691, and issued Brown backs, Red Seals and 1902 Date Backs.  In September 12, 1910, Salem was able to regain it's old charter number 43 and issued 1902 Date Backs dated 11 Apr. 1902--this date represents the last 20 year extension of this bank's charter.  One stipulation of the Acts was that extended banks must issue 'distinctly different' notes.  So 10 Apr. 1922 comes and Salem extends its charter. New plates with this date, 10 Apr. 1922, were created along with the current Treasury combo of Speelman and White (that was sufficiently 'distinctly different' (Congress didn't define distinctly different, so any difference ought to have sufficed)).  They also got to restart the serial numbers back to 1 and went on to issue 12,365 sheets!  So, it's possible that SN 5226 and 5227 also exist as $20 Plain Backs and Fr. 635!!  The Act of July 1, 1922 extended lifetimes of all national banks for 99 years, thereby ending the need for new series to the chagrin of this collector.