Who is responsible for confidential faxes sent to wrong number?

Prudential Insurance is in the news becuase doctors and clinics were faxing confidential patient recordss to another company with an almost identical fax number.

If you are the company receiving the faxes in error, what are your obligations toward the confidentiality of the faxes?

Just becuase someone adds that goofy disclaimer on the bottom that many companies are mandating that says that an unintended receipiant is to destroy a fax received in error, is that binding? What if they just throw the fax away?

At what point does it even become your problem if some clinic you have no relationship with is sending highly confidential information that can be accessed by your employees?