Merging 5 domains into 1 - Duplicate penalty?

[matuloo]

Ok, I have 5 domains with different pages on each of them, I want to merge them all into 1 single site aon 1 of the domains.

What I plan to do is : copy all pages from the domains on 1 domain, and still keep the page online on the other domain.
So basically I will have 1 domain with lets say 100 .html pages and 5 other domains with 20 .html pages each, while the 20 pages on each domain will be identical to 20 pages on the new "combined" domain.

I assume that google will issue a duplicate content penalty to some pages, and my question is : is this penalty gonna affect the whole domain or will it only cause the pages to display only once in the SEPRs(from the old or the new domain)?

I hope someone can explain this to me.

thanks

[Marcia]

Well, in addition to thinking about a duplicate content penalty, how about if Page Rank gets credited to only one of the pages out of each pair of duplicates and because of no Page Rank on pages the rest of the site is toast?

[matuloo]

well, I want to drop the old domains and only want to keep the new combined one, so I will probably delete the old pages on the old domains once the new one got spidered and hopefully the PR will transfer with time to the new domain.

[Hunter]

edited

[SlyOldDog]

The duplicate page penalty is per page. It even filters duplicate pages out which are on the same site. If you add in &filter=0 onto a google query you see all the pages which were zapped by the filter.

So in all likelihood you will be fine, but you might find that the new pages get zapped whilst the older ones stay indexed. And that's not waht you want, right?

I would make a subtle change to each page to avoid getting caught in the filter.

[matuloo]

I will make some small changes on the pages, especially in the links, so when the old page was linking back to the root of the olddomain.com I will change it to newdomain.com, plus I will change some keywords, hopefully it will be enough to pass the duplicate content filter.

[SlyOldDog]

I don't know how the duplicate content filter works but I think it is pretty primative. It's probably a checksum or something.

I have seen many pages with exactly the same text on them but in a different layout happily co-exist without getting caught.