I am having the same problem - send an email (using imap)there are two copies of it in my sent folder.

 

I was having this issue and went to apps->settings->accounts + sync->Google. Once I disabled 'sync gmail' the duplicates seem to have stopped. I think they were sending out twice because my same gmail address is in the mail and gmail account. My gmail is my email...

 

Zombie Thread! It's back from the grave! Lol! If they haven't solved it by now, then they never will. :laugh: