I recognize this was posted about a month ago, but I think I can lend a hand. Try running these three methods just after constructing your action bar:
bar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);
bar.setDisplayShowTitleEnabled(false);
bar.setDisplayShowHomeEnabled(false);
The first just sets the AB to tabs, which I assume you've already done. The second disables the String title up top (I should note that it appears when the app first launches, but then disappears very quickly), and the third shuts off the icon with the same functionality as the previous method. I actually had the same thing you're dealing with occur in my app, but once I ran both of those methods, the extra, and blank, top-most bar disappeared.
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