Hello,
I think the problem might be elsewhere - JoomSEF will always create a new URL, if there exists a different original URL (the only exception is, if the URL differest only in Itemid).
This means, that if you want to have a single URL, you need to make sure, there are no different "source" URLs.
Alternativelly, you may have different "source" URLs => different SEO URLs and the use the newly introduced canonical link feature to tell Google what is the "main" URL.
To be clear about this, please, post here, what are the source links for the SEO URLs already posted.
Thanks.