Replying to an e-mail or letter where two people have the same name

I see varying answers over the web on this.

Hello John and John, Hello John

My last email I went with Hello John, It works as intended and seems like the best way to me.

If two people have the same name and you want to address them in a 'formal setting' try using the part of their name which isn't the same. For this purpose you can use their last names or even full names. It provides are respectable, formal environment.

Example:

Hello Mr. John Smith and John Turner,

Hello Mr. Smith and Mr. Turner,

But if it's not very formal, then you are free to use anything ranging from:

Hello, (a simple hello works too)

Hello John,

Hello Johns, (sounds a bit funny but still usable)

Hello John and John,

Hello Mr. John and John, etc.

Hope, it helped (PS: I used to write formal e-mails officially for my job)