I have been trying different apps and shutting down and returning to text etc. In the three apps I have been having the repeated text problems... Notes, journal, and mail.
I have not had any repeated text in any app as long as I go to the iOS keyboard, instead of dismissing FlickType. My uneducated conclusion is that the dismiss function is the culprit.
Btw, no text has vanished during the time of these tests. Could the dismiss also be the cause of that problem too?