I didn't think the marks would enlarge well, but they aren't too bad.

I knew a very obnoxious and ignorant collector 40 years ago. In her hometown was a 19th c. silversmith named E. Jaccard. She found a spoon with a mark B. Jaccard. It was just an E that degraded to look like a B. She gave a lecture, and said that was silly, and that a silversmith as important as E Jaccard would not let his mark degrade. Well anyway I finally got some spoons of his, he made tons of them, and showed the mark slowly degrade. So things do happen to marks over years.
Having said that I don't see how the V could move to a different position in this mark. But there are obvious similarities: the position of the C and B in relationship to each other, etc. There is one I don't think is visible but the top edge of the B drops a little in all three marks.
Another thing you might notice, the distance between the B and the right edge of the cartouche appears different on the two museum marks, even though they are on the same piece.
So presuming this analysis is correct, the three marks are similar, maybe very similar, but not the same stamp.
I can only come up with two explanations, one is the middle mark is a deliberate forgery. The second is they were cut by the same person.
The first is self explanatory, and the crack was left out deliberately. The second would mean the silversmith decided to replace the cracked mark, and he just cut the mark in a similar fashion.
For the second to be accepted, everything, style, engraving, etc would all have to be very close to known examples of CVB's work, something that can't be done on line.
I will say that in my opinion there is nothing about the beaker that I see that says it is fake, or a converted old piece.
Maurice