Why Is Postmaster's Name Hand Stamped On This 1850's Cover?

The front of this cover is pretty mundane. A decent 11A stamp and fairly clean with just some initials bottom right corner.

The back is what I question.
The only covers I have with Postmaster signatures are free franked.
Why would the PM sign/hand stamp this cover?
Is it common for a PM to have a name "hand stamp"?
Why a second strike of the Northampton postmark?

As for the message written on the flap, I can only make out, Wednesday A.M.

Anyone have insight or comments?

Get (name) note with message for/from (Jim?)yesterday. Maybe.

I think I sort of see:
"Wednesday A.M. Got (name?)'s note with message from you yesterday (???) A.Clarke"

Looks like the PM put a personal note on the back of someone else's first class letter. Not sure how many regulations this breaks; but, probably several since the message is diffidently NOT post office business.

Happy holidays to all,
Russ Ryle

It just dawned on me, the cover is addressed to a ?.?. Clarke. Maybe the P.M. took liberties with this cover because it's a relative?

In the 19th c, mail recipients quite often wrote a note to themselves on envelopes, noting some money they owed to the sender or that they had replied to that person's letter, and so on. This was a simple way of keeping track of correspondence, and I've seen it quite often. Imagine all their envelopes lined up somewhere, allowing the person to double-check each to see if he'd taken care of business regarding each one.

You'll notice that the recipient of the cover has the same last name as the postmaster. They might be the same person or only related to them. In any case, the handwritten note on the back appears to be written by the receiver of the letter or someone related to them and not by just some random "postmaster" which would make the note on the back of someone else's mail a bit strange indeed. There's always the possibility that Postmaster Clarke was writing a note on the back of the envelope to the other Clarke, his relative, who was due to pick up the letter. Hard to know, but adding notes was nearly always done by the recipient themself after they received their mail, so that would be a bit odd.

The postmark on the back of the envelope is simply to clarify the mailing date in Northampton where the letter was mailed, perhaps because postmarks on stamps are sometimes unclear -- and perhaps because this postmaster had just a little extra time on his hands to do that sort of thing! It certainly adds to the cover, so give him a tip of the hat.

It was mailed from Northampton, Massachusetts, a larger town, to what looks like "Chester" Massachusetts (today "Ms" means Mississippi, but back then it was Massachusetts) which was a very small town indeed, hence "Chester Village".

No street address (I'm sure you know most of this) because mail was not delivered to your home. People picked up their mail at the local post office.

Why is there a postmaster's stamp of his own name on the back? I have no idea, but again as with the two postmarks, I'd chalk this up to a very conscientious receiving postmaster who just wanted those who received mail to know who was responsible for taking care of it in the meantime. On the other hand, since it was mailed to one of his relatives apparently, maybe he was simply marking it as a family matter? Hard to know, but it's kind of nice.