So you're trying to leave a review and see that the fields are already filled by the previous user and when you leave your own review, the previous is deleted?
You don't have to worry about that!
This happens when the reviewers have the same IP address.
In this case, you should simply try to leave the review with another IP address than the previous reviewer.
As the plugin detects the reviews with the same IP as one and the same, and, as a result, it's simply being edited when another user with the same IP tries to leaves their own comment.