Here's the deal for launch images which work for all iPads. This should tell you exactly what to do and what you need. You need four images, either the first group or the second one, depending on if your app is set to show the top status bar or not. Notice that the names are the same whether your image has room for the status bar or not.
Description : image width x height - image name
iPad - with status bar turned ON (shows wifi connection, time, etc)
Portrait : 768x1004 - Default-Portrait.png
Landscape : 1024x748 - Default-Landscape.png
Portrait Retina : 1536x2008 - Default-Portrait@2x.png
Landscape Retina : 2048x1496 - Default-Landscape@2x.png
iPad - with status bar turned OFF (more screen real estate)
Portrait : 768x1024 - Default-Portrait.png
Landscape : 1024x768 - Default-Landscape.png
Portrait Retina : 1536x2048 - Default-Portrait@2x.png
Landscape Retina : 2048x1536 - Default-Landscape@2x.png