We have an existing product line marketed through SoftwareShield.com. We are revising and re-branding a very similar product line for a specific vertical market niche and marketing it through another domain. The existing product and domain will of course remain. The existing site is large-ish (>1000 pages) the vast majority (>930 pages) is support documentation. So a total re-write for the new domain is a problem. What we want to do is simply "rebrand" the site for the new domain and post it.
The end result would then be two distinct sites with near identical offerings - both of which are perfectly legitimate and independant. The problem is, I am fairly sure Google will freak-out and penalize us for duplicate content if we dont make them "different enough".
Q1: What do we need to do to reduce the chances this will happen without re-writing the whole site?
Q2: How can I quantify the changes necessary to minimize any Google penalization for "duplicate content"?