Oh the good old duplicate content question.
Firstly let's start off by stating there is no duplicate content penalty so don't panic.
Sometimes on a website it is pretty much impossible to provide unique content for every product especially when the product has variations. Let's take blue widgets and red widgets as an example.
The specification and product description makes sense to be the same so you won't be harmed for that in the slightest. The issue comes if you want red widgets and blue widgets to rank separately as they will compete against each other to a degree.
One suggestion which may be suitable is to create a widget landing page and list the product description there with links to each colour from there. All products for widgets would link back to the landing page helps give that page more power to rank by the internal linking structure.
The other option is to have your product page as a variation production so you have 1 description and a dropdown with the colours available.
However, both these ideas may not be suitable for your setup so if that's the case I would provide links to the other colours from the product page so that it makes it easy for users and Google to understand there are other options available. (see also type link)
Make sure your title contains what is unique so in this example "Blue Widget" and "Red Widget" which will help to get both pages ranking