This is an interesting subject and seems to have nothing to do with the utility of the "new" barrels. Just the name and number. Hmmmmm

Who is being dishonest when a gun is rebarreled by another , and the original rib is used with it's markings of the original gun ?

OK , who is being dishonest when you commission your Best gun to have new barrels put on by that same Best maker. Sometimes, I'm sure, that Best maker sends your gun out to have new barrels fit by someone else. It could even be Mr. Another in the paragraph above. Now when the newly barreled gun is returned to the owner, exactly the same work as in the paragraph above has been done. In this instance we are led to think the new barrels are somehow superior to the one's above. In what way, may I ask ? Maybe because the Mr. Best charged the gun owner multiples of what Another charged, Mr. Gun Owner feels he somehow got a superior product. Now, all that is is good salesmanship, the rest is Poppycock.