The same duplicate home page mystery has happened to me:
http://chineseherbalbath.com.au.
I have inherited this website in an attempt to help promote my boss's new business. He had the website built by a "designer" who charges too much for any changes. I thought I was on top of it until... 2 x home pages appeared!!!
The only thing I was doing at the time is editing a child page to a parent page on the nav menu (health topics), which I'm assuming may have originally been a blog page?!
I've read lotsa forums and I've tried customising the menu but it doesn't affect the double home pages. In fact adding a new menu hasn't affected anything!
I've also made sure the setting->reading page's radio button is selected to static home page but nothing changes.
If it is a hard code somewhere I've checked for a header.php but can't locate this anywhere under templates or styles in settings? If it is a code issue, please type clearly, I'm clueless!
Any other suggestions?