Will GOOGLE penalize eventually if you have multiple sites(3) in top10 that sell the same products and are owned by same company but content is different?
I have 3 links on Google Page 1 for the se term "hire #1 seo writer" In fact when I search that term on Google I am present in the top 6 links. So I would have to say in my experience No! (it should not make any difference) If you are delivering the goods by supplying the SE's with the best info for a search term then that's the way it is!
They don't penalise but sometimes you will see that all 3 sites may not rank for the same keyword if the keyword is competitive - this is of course if you cross link the sites and Google is fully aware that the sites are related.
It is not a problem as long as the sites have different content and design. Mainly text as long as the text on the pages is different and phrased different .