To prevent users from linking to one version of a URL and others linking to a different version (this
could split the reputation of that content between the URLs), focus on using and referring to one URL
in the structure and internal linking of your pages. If you do find that people are accessing the same
content through multiple URLs, setting up a 301 redirect from non-preferred URLs to the dominant
URL is a good solution for this. You may also use canonical URL or use the rel="canonical" link element
if you cannot redirect.