Product variations best practice?
I'm doing some work on a foxycart e-commerce site selling automotive headlight bulbs amongst other things.
I've noticed that a lot of the site's competitors are dealing with variations in fittings by listing the product in each size. For example in terms of headlights, they list Product A Size 1, Product A Size 2, Product A Size 3 etc..
Surely this is bad practice, especially as the content is duplicated. Shouldn't google be punishing them?
The reason I'm asking is that the site I'm working on lists the products as normal and then uses a drop down box for the customer to select the size they require.
Which method would you use?