Duplicate index page? Does anyone understand this?

My website appears to have two index pages which means that I have duplicate content.... not good for seo...... If visit visit this page... http://seo.ibeaminc.com/seo-site-validator/ ...and enter my web address: www.imbackcatering.com, you will see in the results that it says i have: 1) imbackcatering.com/ and.... 2) imbackcatering.com/index Hope someone can explain how I only index just one of these... Thanks in advance