It sounds like you are using some tool to crawl your site and produce a report. Tools are not perfect.
In the footer of most mojoPortal sites is the "Printable View" link which has the url with skin=printerfriendly
I do not believe this link hurts SEO at all for 2 reasons
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the link has rel='nofollow' on it and googlebot knows it should not crawl that link even if the tool you are using still crawls it
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even if the page is viewed with the printer friendly parameter in the url we have a canonical link in the head that tells search engines the correct url for the page <link rel='canonical'
Search engine bots such as googlebot are very smart and use these things so I think the report you produced is wrong. If you really think it hurts, you could remove the printer friendly skinpreview link from the layout.master file of your skin.
Hope it helps,
Joe