*Loan,banking and credit>>>insurance fraud

Is it a common for a doc use insurance fraud?

Let's say a patient dies that has health insurance but another patient needs an expensive operation, otherwise they die, and doesn't have insurance. Is it common for the doc to use the deceased persons insurance to help out the non-insured person so that they can live? If so, does this happen often, or very little?

Yes. Many are forced to if they want to give their the patients top health care. Health insurance is a fraud in itself.

However some physicians do it only for monetary gain...

Doctors and hospital often pad the bills.
lol, that was on scrubs, its common, but not in the way you described.
it probably does happen- but only little, it is identity fraud, even if the person has died- sadly it's illegal, but hey- it's the american medical system, i wouldn't blame doctors who did...