Can you use the same keyword for two pages? (eCommerce SEO-copy)

So, I typically don't use the same keywords. But my client has a huge furniture eCommerce site (700+ products), and they want titles that are more uniform.

For some of their products, there are very little relevant keywords (e.g. 8 products, but only 6 relevant keywords). Will there be any penalization if I use the same keyword? (just duplicates, no triples)

Or would you recommend choosing a word that isn't searched? I'm hesitant to do that, but would love other opinions.

[EDIT] - the two titles i'm looking at are almost identical (just a different color stain) - and they're not looking to combine the products at the moment.