同时拥有www.sitename.com和www.sitename.com/index.php网站链接会影响SEO吗？

I was told this by a coworker, and I was curious if this was true. They requested I change any links on a site that point to the homepage as 'index.php', I'm assuming because they think it will treat the two different URLs (www.sitename.com and www.sitename.com/index.php) as duplicate content. However, I don't think that this is the case. What say you, StackOverflow? I was told this by a coworker, and I was curiou