Domain Aliases - Does this hurt google ranking?

I want to know if i have two domain aliases pointing to the same site, does google pick up both or just one?
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Julian M.Web DeveloperCommented:
Having multiple domains pointing to the same site is no problem as long as they are not mirrored sites. With mirrored sites, you risk getting a negative affect in search engines.

To do it correctly, you would need to have one domain pointing to the site and have all the others redirect to the first using a 301 (Moved Permanently) header/status code.
Julian M.Web DeveloperCommented:
Here it is form the horse's mouth:

"Don't create multiple pages, subdomains, or domains with substantially duplicate content."

"Duplicate content"

Most of the other major search engines have very similar guidelines.
Bernard S.CTOCommented:
Note that with Goggle webmaster tools you can tell to google search that you have a "preferred site", eg if it finds the same page under and, you can tell GG search to index just
And I would probably use that also in your case
This is around page if you have registered with webmasters tools. otherwise you need to register first at

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