@Kumary
I was also facing many issues with wazapp 0.9.19. What you stated above was part of it too.
Its like if you copy and past some text in the text input box and if you try placing the text input cursor some where else by clicking in the text input area then the whole text gets pasted again, they clicking somewhere else and it pasts again. Not sure if that happened with you but it did happened with me.

More so i was plagued with a unique problem where when i would press send after typing text, it would just disappear from the Input box. I was just not able to send any text for a very long time. Did loads of experimenting and finally decided to solve it by going one step at a time. 1st was rest to factory setting, then a comprehensive rest deleting all data n if that also did not work then Flash it.
But fortunately "Clear Setting" worked like a charm for me.

I highly recommend it to you as it only resets the basic setting keeping almost all user data Intact.

Go to Setting>>Reset>>Restore Setting>>Yes

I didnt even need to unInstall n reinstall wazapp after that. Its working perfect since then.