Duty dodging has been debated on the forum in the past, but I would like to offer a new angle.
Most collectors of silver are in the belief that the striking of multiple makers marks was just an avoidance of the duty payable and nothing else. This is something I have always found hard to accept as the makers marks in question are often still legible, and with the heavy penalties payable for such an offence why would you sign your misdeed?
Perhaps the answer is much simpler than may be imagined and also might explain why I have seen so-called duty dodger marks that were registered by the silversmith at Goldsmiths Hall long after bottom marking had ceased.
This is a snippet taken from a publication regarding a robbery of silver spoons. The crime is of no interest to us here, but the terminology used is.

To be new christened, by erasing the crests and reversing the handles, this would imply to me that the spoons in question were to be converted from the Hanoverian style into the Old English pattern.
Now, when reworking the spoon into the new fashion, how much work is involved? Besides the obvious turning of the terminal into the downwards position, most Hanoverian examples would need to be extended as they are usually slightly shorter than its Old English pattern counterpart. The reworking of the entire stem would be required, as where the old hallmarks were situated on these bottom marked pieces, it would cause a weak spot if the spoon was just hammered out to achieve the extra length. During this refashioning the hallmarks would have been completely lost, but customers would expect their precious silver flatware to be marked in some way. They could of course have their pieces re-assayed, but this would lead to further expense and delay and they would now have to pay the required duty, just to have the new hallmarks applied. There was no legal reason to have the items re-assayed, nothing had been added, only refashioned.
I'm sure there are real duty dodgers, but these will be the ones whose marks are completely illegible, and on reflection all of the duty dodgers that I have noted with legible marks have been in the Old English pattern. I believe these are not illegal pieces but just the result of bringing the piece up to date.
Trev.