I have 2 sites: example.co.uk and example.com
Same template design, but the .com has unique content aimed at US/CA users. The .co.uk has unique content aimed at UK users.
Not just simple rewrites of each other. The product range is different for each side so the content doesn't even come close to matching.
Each site has about 50 pages with the main, 5-10 category and contact pages all interlinking. Nothing really when you consider the interlinking done by most companies that span a few countries.
.co.uk receives about 6000+ visitors a month and ranks in the top 10 for nearly all it's keyphrases. .com receives about 100+ visitors a month and isn't even in the top 900 for it's keyphrases - even though it has 3x the backlinks.
Any clues?