Double menu on smaller screens

Hi,
I’ve muddled through to this point in my website, using a child theme of the twenty twelve theme,
http://www.jonathandalton.ie
and am relatively happy with it.

I’ve installed the responsive-select-menu plug-in in the hope of replacing the default twenty twelve grey menu button on mobile devices and smaller screens, however both appear rather than just the responsive-select menu.

I’ve read through other similar problems on the support pages but although I could see other similar problem I could not see any solution to my praticular problemp. I’ve played about a little with no success.

Any help anyone could offer would be greatly appreciated. Considering I could at best be kindly described as a novice if that help was worded for a bit of an idiot, I would be even more grateful.

Thanks in advance and what not,
Jonathan.

http://wordpress.org/extend/plugins/responsive-select-menu/