Do you need two doctors to certify for hospice or can just the medical director of the hospice certify a patient?

As far as I know, only one doctor needs to certify a patient for hospice, and it can be the patients doctor that does this. I've work with hospice for 20 years, and in that 20 years I've never heard that it took two doctors or just the medical director with hospice to certify a patient to be enrolled in the hospice care program. The patient does hwoever need to be deemed terminal for the hospice care program to be considered.