In the United States if the person insures an article and then claims a loss of that article, the insurance replaces the missing/destroyed article. If later on the item is found the original is owned by the insurance company. The person who purchased the policy doesn't get to keep both.
Of course if the item was so valuable to be priceless the insurance company would be open to an exchange of items or money.
But if they suspect fraud...then it becomes a legal matter.
Even when a life isn't involved it can be a source of dispute: http://www.artnet.com/magazineus/news/spencer/spencers-art-law-journal5-7-10.asp
INSURED V. INSURER: WHEN STOLEN ART IS RECOVERED, WHO OWNS IT?
Kenneth S. Levine
This essay is about the word "subrogation," which frequently appears
in insurance policies. An insured painting is stolen and the insurance
company pays the owner’s claim for the value of the painting. Many
years later, when the painting is recovered, its value is many times
what it was when the insurance claim was paid. The insurance company
takes the position that it owns the painting, while the owner says I
own the painting, less the value of the insurance proceeds received.
The resolution of this dispute depends on the meaning of the word
"subrogation" in the insurance policy.
When life insurance is involved, the item being replace is the lost stream of income. The question of returning money and how much would be a legal issue. They would also want to know if there was fraud, and who was involved.