Sometimes it makes sense to have more than just one website, even if they are all for the same company and have lots of similar content. Why would you want to do this? If you can get two or more sites ranking well, then you have basically blocked out the competition and diluted search results a bit.
Say you sell garage doors, and have a really good site that ranks well. Then you add another site with a different url, which has different content, but still about your company. Once this site starts ranking well also, you can target a different set of key words, so now you have a much broader set of key words, or you can rank for the same key words as your first website. If someone searches for garage doors, if both sites show up, you increase the chances that someone will visit one of your sites – it’s that simple.
This only makes sense if you can design and update the content yourself, or don’t mind paying someone else to design the site for you. Don’t go half way, setting up the site yourself but then not getting around to building it. Either decide that you will do it, or that you don’t have the time or don’t want to spend the money. Here’s some food for thought though – if you get one or two sales due to having a second site, is it worth it?