and testing for the functionalities. When creating a comment with my user credentials, the comments are duplicated. Prior to the third test, I re-installed the component based on another's post that resolved a slightly different comment error.
I tried to comment and I saw that the comment form is double posting indeed. I tried with the default template and I didn't see that behaviour. This could be either related to your template overrides (the template developer might already have the solution) or to another extension/plugin.