In a case like this (with major brand sites as those listed) you won't be dealing with a penalty insomuch as you'll be dealing with a case of content being ignored. For example, if a local shop has the same content as Amazon, Amazon will generally win.
I can't possibly answer the question better than Matt Cutts himself so he is:
http://www.youtube.com/watch?v=LgbOibxkEQw#t=77 You'll notice that the focus of what he's saying is on unique content and giving Google a reason to rank you. This is a case like that noted in my comments about strong outranking weak; if a site is up against a strong site - Google is going to rank the one they believe is the most trustable and that will be the biggest brand (generally).
Now, I cannot for the life of me find it but I know that recently Google has comment elsewhere that they may look to user intent. If a user or their query indicates a preference to online buying then they would rank Amazon and if they tend to imply a local purchase then a local site would rank with exactly the same content. I know that's from recent comments from Google but I cannot remember where I saw that. Sorry - not a great source.
Either way however, the stronger site will win if the content is all up at the same time and the stronger site may even beat original source if Google decides it's more reliable or fits a searchers intent better.