Hi, anyone has experience having more than 1 website serving different geographical markets, say 80% of the web content are similar but 20% are customized for the particular market e.g. .com and co.uk for USA and UK respectively. Will the websites be "penalized" for having duplicate content by the search engines? Thanks in advance.
If the content is similar then yes, it will have an effect. Create fresh content for both sites and apply rel=nofollow attributes to all links between the two sites.
Customize content for different market is not a problem as long as you don’t try to show a different content for google bot. And regarding duplicate content, its sad that actually duplicate content could beat the original content in SERPs.