If it is annoying, modify the preferences of that account - right click (Control-click) on the account and uncheck "Save draft on server".
Another option is to delete the account and create it again. Now with all updates the account will be created correctly. That's what happened on one my computer. On another one the system update fixed the problem.
I heard that there was a bug and this bug was fixed. I do not know if this true or not. Anyway, it does not happen any more on my computers.