Need some help related firebase!

I am making an app for chat.
I basically used chatview but I have captured an error after compiling apk.
I have been working on it for three days but couldnot found any solution.
The error is very strange for me.
I used firebase to get chat.
I gets but adds received chat not send chat two times.

As you can see in screenshot.
Can anyone tell me the solution?

Share your blocks :confused:
It would be better to get proper solution …

Here are the blocks @OfficialDjJohn

After more than two hours spending on computer I was at place where I had started.
The problem is still continued.
It seems to be a bug of firebase or I am doing something wrong.
Please help me!