Mr. & Mrs. <lastname>
You can address them simply as President of whatever the company name is. You can then follow with the rest of the address.
Dr. & Mrs. John Smith
Dr. Mary Smith and Mr. James Doe
if addressing an envelope it would be to the Reverend Canon or just Canon. His wife would be Mrs... The oral address would be Canon, and his wife Mrs.....
How about Mr. and Mrs.
Drs. _______ and ________ Smith
Type your answer here... Mr. and Mrs. Mark Henderson
Pastors George and Martha Maloney
Address the man in the same manner as if his wife were not a dentist.
I would address it to: Sir and Mrs. John Doe Street address City, State and zip code
That would be: "Dr. John and Mrs. Jane Whomsoever".