No, double dipping is not legal. An injured party can only recover his or her actual out of  pocket medical costs. So, say that you incur $30k of medical costs and pay $4k of it, between copays, deductibles, etc.--the rest is paid by your own insurance. You could recover the $4k from the at-fault party or his/her insurance--and your own insurer my be able to recover the other $26k from the out fault party to reimburse what it paid out to you. Between you and your insurer, you only recover an amout equal to the total damages, and you do not receive more than that portion which you paid.That's not to say that errors or mistakes don't happen--undoubtedly, some parties have recovered more than their fair share. But that's not the law.