Well - insurance companies also keep precise records. Somebody, likely Lloyds, paid a claim or two on that. Also consider humans are a strange breed. We go to great toil and expense to dig up gold and silver from the ground, streams and deep caves. Then, we melt it down into bars and bury it again. So it raises a sort of interesting question. If you can prove how much money you had on ship x, and its general location in some effect you still have your money. Admiralty law is probably part of that concept?
I think the ancient law of 'Finders keepers, losers weepers' should apply.