Hi Michelle & Blake
SEO has been changing a lot, especially over the last few months in particular. I would encourage you to optimise your product pages with clear structured categorised titles. They will inevitably incorporate keywords, but don't focus on the keywords as such, focus on clearly explaining the products to your site visitors in the subsequent product description.
In the future, sites that use multiple keywords per product are not going to gain an advantage by doing that - in fact it may even have a negative impact. SEO needs to be about writing for your audience, your site visitor, and making sure the content of your pages answer the questions they may be asking about your products and perhaps what related products you have.
It may hep your SEO in future to use structured data markup with your products (see http://schema.org/) but at this stage focus on getting your pages right as they are.
Using the same keywords for multiple products under the same category will be fine, but just distinguish them by using other words that describe them. For example, red sofa, black sofa, white sofa all repeat the word "sofa" but they are different.
Duplicate content will only come into play if you repeat a large proportion of the content of a page across two or more other pages on your site. If you focus on providing good clear descriptions for each product, you won't go far wrong.
I hope that helps,
Peter
