My client is generating templates for his eBay template based on content he has on his eCommerce platform. I'm 100% sure this will cause duplicate content issues. My question is this.. and I'm not sure where eBay policy stands with this but adding the canonical tag to the template.. will this work if it's coming from a different page i.e. eBay? Update: I'm not finding any information regarding this on the eBay policy's: http://ocs.ebay.com/ws/eBayISAPI.dll?CustomerSupport&action=0&searchstring=canonical So it does look like I can have rel="canonical" tag in custom eBay templates but I'm concern this can be considered: "cheating" since rel="canonical is actually a 301 but as this says: http://googlewebmastercentral.blogspot.com/2009/12/handling-legitimate-cross-domain.html it's legitimately duplicate content. The question is now: should I add it or not? UPDATE seems eBay templates are embedded in a iframe but the snap shot on google actually shows the template. This makes me wonder how they are handling iframes now. looking at http://www.webmaster-toolkit.com/search-engine-simulator.shtml does shows the content inside the iframe. Interesting. Anyone else have feedback?