Letter Writing Query?

Question

When you begin a letter to a pair of people with the same surname and the same sex, aka, Mr J and Mr F Smith, what do you put in the "Dear" section? Your don't put initials in that part of the letter, and writing "Mr and Mr Smith" seems silly. I have used "Sirs", is that correct? And what if its Ms J and Ms F Smith?

Answer 1

If it's men: Dear Sirs or Gentlemen or both their names

If it's women: Ladies or their names

If they are co-workers: Dear Co-workers or Associates

If they are friends of yours: Dear Friends

If they are customers: Dear Clients

Answer 2

Dear Sirs is the most right thing to do. You did it right. Or you can also put, Gentlemen. But the first one is the most appropriate and safest way to do.