human visitors. Footers are often the first place to look for violations of this principle. The reason this is important is that the way multiple links are evaluated is unreliable and variable. Technically, two links to the same page should pass double the PageRank to that page based on the original PageRank formula; however, it is not reliably known if this is still the case. If not, multiple links to the same page can be ignored or
worse, purge PageRank. I find the latter unlikely, but unknowns are never good. Also, if the extra links are just ignored, then you've cluttered your page and forced your visitors to make more decisions for no reason. Additionally, multiple links also make the anchor fax number list text unreliable. Sometimes only the first link's anchor text is counted, but it is thought that at other times both can carry weight. So basically adding multiple links for SEO from an anchor text perspective is as likely to cause trouble as it is to help.
The only exception to this rule that I can think of that is more or less globally applicable is the homepage. The reason for this is that the first two links to the homepage are usually the logo and a link with the anchor text "Home". None of these elements are particularly SEO-friendly except for their prominent placement on the page. So adding a third link somewhere containing keywords can help engines understand that the target is not "home" but "widgets".