Yes, it can. In fact, your competitors can easily use this Achilles' heel to overtake you. However, you can safeguard your website now!
Merging, renaming, and especially moving web pages and subsequently, web addresses are commonplace. While the methods of redirecting URLs are many, there is only a single right way to make it search engine friendly. The most efficient and effective Search Engine Friendly method, 301 Redirects.
Canonical Domains & the Problem with Duplicate Content
Canonical domains, also called subdomains, allow you to have other domains based off of your primary domain. They are part of the domain name system (DNS). An example is info.yourwebsite.com where 'info" is a subdomain of the domain 'yourwebsite.com'. Here, the DNS entry for the domain yourwebsite.com points to a specific IP address on a server.
Canonical domains serve as aliases to domain names. Again, info.yourwebsite.com points to the same IP address as yourwebsite.com since it does share the same host server (where you upload your website files). Other possible canonical domains of yourwebsite.com are email.yourwebsite.com, store.yourwebsite.com, and of course, www.yourwebsite.com.
These subdomains can also be used as individual websites. Yahoo, for example, uses subdomains for their different services like mail.yahoo.com, messenger.yahoo.com, and more. These subdomains forward to another location.
So what is the dilemma?
Well, to both the DNS system and us, http://www.yourwebsite.com and http://yourwebsite.com bring up the same web site since they are the same. Unfortunately, to search engines, they aren't the same since they treat subdomains are entirely different websites but with duplicate content. Therefore, they will be ranked lower since search engines penalize for duplicate content.
Beware of Your Competitors & 301 Sabotage
Your competitors for search engine ranking can easily exploit the problem above. They can find further instances on your website that use www and non-www links. They can link these problem spots, again unintentional duplicate content, to further reduce your rankings. This is known as 301 Sabotage.
How to Protect Your Website & Ranking
The first step in protecting your website and ranking is to see if your website needs protection at all.
Step 1: Enter your website URL http://www.yourwebsite.com (replace 'yourwebsite.com' with your own domain).
Step 2: Watch the address bar to see if your destination is www.yourwebsite.com or yourwebsite.com. Keep the answer in mind.
Step 3: Now enter http://yourwebsite.com and see where you land.
After checking both http://www.yourwebsite.com and http://yourwebsite.com, did you land at the same URL (in this case either www.yourwebsite.com or yourwebsite.com)? If in both scenarios, you land at the same URL, you have no problems. As long as you land at the same place, it really does not matter how you got there.
For example, as long as www.google.com and google.com land on the google.com (without www), everything is fine.
However, if you land on different pages but with the same content, your website is open (whether intentionally or not) to exploitation via 301 Sabotage. Don't worry, all you need to do is implement a 301 Redirect to protect your website and ranking.
How to Do 301 Redirection
The single correct method of redirecting your domain name to protect against 301 Sabotage and lowered search engine ranking is HTTP 301 (redirection header) or 301 Redirection.
HTTP Protocol is basically a set of headers that makes the Internet work. HTTP headers are seamless. Therefore, they are usually invisible to your website visitors. Yet they are a vital part of web server to web browser (IE, Netscape, FireFox, Safari, etc.) communication. Since they are exchanged before any web content, such as an HTML page, is sent to the browser, they are called headers. Basically, they appear at the head of the document.
Part of the standard HTTP headers control redirection. These are known as 3xx Headers since they are numbered from 300 and on (300, 301, 302, 303, and so on). In particular, the HTTP 301 header designates that a web page has been moved permanently. Another header usually immediately follows and communicates a new location that the web page has moved to.
Everyone (and everything) from website visitors to search engines now know that a web page or domain name is no longer in use. It also knows what the new location to be used is. Search engines, specifically, will automatically index the page as the same page.
While there are many techniques to do a 301 Redirection, some are best suited for forwarding entire websites and others for individual pages. The three ways to do a 301 Redirect include:
The PHP header() function for web server's that support PHP
The mod_rewrite function for Apache web servers
The built-in forwarding that your web host might provide
Before testing any of the 301 Redirection methods above, you should first clear your web browser's cache. This will allow you to see if it works or not. FireFox web browsers especially need to have the cache cleared or you will get an error message saying the URL Redirection limit has been reached.
Conclusion
As you have read, being proactive about problems that may lower your search engine ranking is not too difficult. Implementation of 301 Redirection is a simple and easy way to make sure your website and ranking is protected. In fact, 301 Redirection is the single correct way to address 301 Sabotage and other issues, whether intentional or not, that may threaten your search engine ranking.
To get further instructions, including actual code that can be used to create a 301 redirect, please visit my web site.