Who's Dave, and why would he know?
It's not illegal to make multiple insurance claims at all. You can have as many life insurance policies as you like, and when you die a claim is made and they all pay out.
What is naughty is to have multiple insurance policies for the same thing, and to claim off them individually without telling the insurers about each other. (Like in the good old days of hiring a derelict ship & a foreign crew, over-insuring it with multiple policies, than making a killing when it sank).
Our model insurance policies have 'contribution clauses' which state that, if cover is provided by another insurance policy and a claim is made, each respective insurer would only pay their share of the claim.
If you're forced to make a claim, the insurer may will ask whether there are any other policies that could cover the incident.
If you do have cover with another policy, the insurer could ask the other company to make a contribution. The companies would then calculate a proportionate amount of excess for both policies.
This also means that you would be making two claims, but not illegal as the insurers know about it.
If you like long words, read page 4 of this...
http://www.cila.co.uk/files/contribution.pdf