Fighting duplicate comments

Hey.

You must either enter the flood-control (the second and subsequent comments with the same text from one user to one post / comment in the database do not record), or deselect the button to add a comment after clicking on it.

But it is impossible, all the time my comments are duplicated - click on the button, there is no reaction. Well, I think, the touchpad failed, I click again - op and two postings.