Hi,
Duplicate content issues are created when the same content appears on two different urls. So if your content appears on www.yourexample.com/brandaproduct and www.yourexample.com/brandbproduct, then that's when it's an issue.
You can do this by changing dynamic elements via personalisation, but it's not necessarily easy to do, and could well end up risking a penalty for masking/cloaking if there's an error.
Personally, I'd rethink why you're running both brands - are they targeting different audiences/locations?
If there's no differentiation between the two brands, then there's no point in having them. But if one is targeting a different demographic, then there's a reason to create unique content which will appeal specifically to their audience. The actual product and data may be the same, but the benefit of bespoke content for the right audience will be an increase in conversion rates to actually purchase your services, rather than simply avoiding any SEO penalties...
It's an approach which is done by many, many companies. For example, I worked for a major UK publisher with 5 magazines all covering the same topic area, but one was aimed at beginners, one was for advanced users, and others concentrated on specific niches within the market...