A lot of times, webmasters will buy multiple domains to take advantage of the possible variations of their specific keywords. This is fine as long as in doing so, the correct methodology is implemented. If I buy domain A and create content for it and then buy domain B and use the same content, I now have what is considered to be “duplicate content”. This is not to say that Google or Bing will necessarily penalize anyone for doing this, but there will certainly be ranking ramifications if your domain configurations are not set up optimally.
For instance, Google may decide to index content from one site, content from the other site and combine the results in the results pages. Link value tends to get split between all the different incarnations of your content and the site becomes less of an authority; completely diminishing all of your SEO efforts.
When it comes to duplicate content, most webmasters don’t realize the negative ramifications from it. There will usually not be any kind of “penalty” or “punishment” imposed by Google, but there will be the reduced effectiveness for their primary keyphrases.
How does one tackle the problem of duplicate content? The first option should always be to avoid having duplicate websites in the first place, but the main ways to remedy the situation are either; 301 permanent redirects from the duplicate domain to the preferred domain and the second (and probably the tougher) would be to just have two distinct websites with completely different content and goals. One website could be for your consumers and the other could speak to/sell to your business clients.
Business owners will often purchase multiple domains to take advantage of all of the keyword potential that is to be had. For example, a webmaster that sells horse shoes online (I’m sure there are some) could own www.horseshoes.com, www.Ilovehorses.com and www.mykingdomforahorse.com. In this example, there are different reasons that this webmaster/business owner owns these different URLs.
The first reason could be that they all represent completely different business entities and/or types of websites and the content on each one is distinctly different from the other one. The person that owns and/or operates these websites has no intention of ever combining or redirecting them anywhere else. They are all websites with completely unique objectives that just happen to have something to do with horses.
The second reason (and usually the most common) is that all of these websites have the same or similar content and all share the same purpose; to sell this business’s horseshoes online. The problems that can incur if not handled correctly is content filtering or, even worse, duplicate content penalties in the search engines. To avoid this, one can employ certain strategies.
Firstly, you can identify which domain you prefer to use as the main domain and simply redirect the other two URLs to it with a 301 redirect. The second and probably the least practical solution is to keep them all separate, but make sure there is absolutely no content overlap. Another scenario would be to use the rel=”canonical” tag which (as of December 15th, 2009) you can use across multiple websites. While the rel=”canonical” link element is seen as a hint and not an absolute directive, Google says that they do try to follow it where possible. This tag lets you set the preferred version of a domain with highly similar content and is used in the section of all non-canonical versions of the site.