I’m guessing you created a new Page called “Home” and set your home page to the static Page you created.
If this is the case, then the navigation would show 2 tabs for home for this reason; The theme default links to the home page as a tab, then lists all of the blog’s pages as separate tabs. So since you created a page called Home, it appears to shows 2 tabs as Home.
Try this: Edit your theme’s file: header.php. You should see some code where it shows something similar to this:
wp_list_pages( );
It probably has other parameters in the code, what you need to do is tell it to exclude a page. To do this you will need to add something to then end the code like this:
wp_list_pages('sort_column=menu_order&title_li=&exclude=5');
Where 5 is the page id you don’t want to show. To find the page id for your home page, login to your blog’s admin, go to the edit of the page and look at the URL in your browser’s address bar. You should notice that it has post=5. The number that it shows is your page’s ID.
Update the code of your theme’s header.php file and you should now only see 1 home tab.
Hope this helps!
~Anthony