I got the answer for this.
I have to write the code in this way that after pressing back button, edit text will be gone out of focus. The code will differ according to the implementation that is why I am not providing the coding solution. You just need to take care if your EditText box asks for focus somewhere else in your code. Which sometimes cause this bug. You will find that this bug of android in which its adapter only keeps the current items of the view in the memory; causes the bugs with values being removed from the EditText boxes and values being copied to other EditText boxes.
ALl you need is to take care if your EditText boxes are somewhere else requesting for the focus - this is the key.