Duplicate mails sent after editing Outbox mails

Hi, I have been using the delayed send feature in eM client (v7.0.27), by disabling the “send immediately” option in the settings.   Using IMAP (port 143) & SMTP (port 25) on a normal hosted email account.

I’ve also deactivated the Conversation mode according to your employee Maurice Hester’s, post
(Go to Menu -> View -> Conversations -> and Disabled Conversations/Show Conversations in Message Detail Only). 

I’ve since found on a recurring basis that when I edit a mail that is sitting in outbox (supposedly unsent) because I want to amend detail or fix an error - that after editing and sending, I find two versions of the mail have been sent in sent folder. The unedited version as well as the edited one, essentially sending 2 mails to the sender, making me look quite unprofessional. I have verified that recipients received both emails.

Perhaps the mail was actually sent even though it was still in the outbox when I clicked it to edit, but really, I’ve been doing this for years in other email software and never experienced this - Is there a way to eradicate this error?