I am not sure, but I see a weird integrated mobile drop-down search form of some sort, that is not visible by default. I guess it is also loaded as the theme search bar and the plugin automatically overrides it. The mobile menu is then tries to make a duplicate of some sort, that probably causes the multiple outputs.
I can’t exactly tell by the screenshot though. Maybe adding the search shortcode manually would be the best idea, as the integrated search form seems to be strictly designed for this theme.
Best, Ernest Marcinko If you like my products, don't forget to rate them on codecanyon :)