a couple questions regarding a pair of type 38s

hello all,
I recently won a pair of Arisakas on gunbroker and had questions about both of them.

one of them is a type 38 long rifle that supposedly had its mum overstruck with concentric circles to remove it from military service for use in civil services. however on closer examination this does not look like concentric circles at all. is there any chance that this was just a really sloppy stamping or was this just a fancy method of removing the mum post war?
https://www.milsurps.com/images/impo...81581855-1.jpg

the second rifle is a type 38 carbine. the post claims it's a bringback with mum intact but I've never seen such weak stamping of a mum and type markings before. also there appears to be a ring which I believe to be a duffle cut which would confirm that it's a bring back but raises a new set of questions. based on the following pictures I have the following questions:
https://www.milsurps.com/images/impo...75981794-1.jpg
https://www.milsurps.com/images/impo...44378100-1.jpg
1. is this an intact mum or just a poorly removed one covered up with white chalk?
2. is this a duffle cut just behind the tang?
3. if it is a duffle cut, how does this affect collectors/monetary value.
4. if it is a duffle cut, is there any risk to firing the rifle?

School rifle marking on mum of first
On second, the mum looks intact to me with a lot of wear on the top of the receiver. The Japanese letters are also thin.
I have never seen a duffle cut behind the tang but that doesn't mean it isn't one.
I would say that particular cut hurts the value significantly. Duffle cuts are traditionally under the barrel band. The rifle is shortened by taking it out of the stock. This one can be seen, and it weakens the rifle.
There is some risk to shooting this rifle because that area receives a lot of stress when it is fired. It really makes a difference in how it was repaired.