We have a website that allows users to list items for sale. Think ebay - except we don't actually deal with selling the item, we just list it for sale and provide a way to contact the seller.

Anyhow, in several cases sellers maybe have multiple units of an item for sale. We don't have a quantity field, so they upload each item as a separate listing (and using a quantity field is not an option).

So we have a lot of pages which basically have the exact same info and only the item # might be different.

The SEO guy we've started using has said we should put a canonical link on each page, and have the canonical link point to itself. So for example, www.mysite.com/something/ would have a canonical link of href="www.mysite.com/something/"

This doesn't really seem kosher to me. I thought canonical links we're suppose to point to other pages. The SEO guy claims doing it this way will tell google all these pages are indeed unique, even if they do basically have the same content. This seems a little off to me since what's to stop a spammer from putting up a million pages and doing this as well?

Can anyone tell me if the SEO guy's suggestion is valid or not? If it's not valid, then do i need to figure out some way to check for duplicated items and automatically pick one of the duplicates to serve as an original and generate canonical links based off that?

Thanks in advance for any help