the problem may be partly what ergophobe suggests wherein you need some unique text on that page such a way that SEO-Generator can find it and use it (or override the auto generated meta description for specific urls if that's an option.)
another problem may be that joomla or one of your installed extensions is generating links to and serving content to requests for non-canonical urls.
solving this requires preferably a 301 redirect to the canonical url or a link rel canonical element referring to the canonical url.
what is the difference between specificwidget.html and specificwidget.html?limitstart=0 (for example)?
if there isn't a difference in the content served by those urls then you shouldn't really be referring internally to any urls with the ?limitstart=0 parameter string and should probably be handling that in a browser cookie if it is required to maintain a state.