Unable to open both main.xml files from layout & layout-land at the same time?

Answer 1

This is because the two different files represent the same layout just in different configurations. If you want to edit the landscape layout you have to click on the 'Layout' tab at the bottom of the editor and select the 'Config' that you want to edit. Depending on the configuration you select you'll have the layout xml editor fill with the correct contents from each file.

Answer 2

Right click on main.mxl and choose 'new editor'- this will create another main.xml which you can replace with the landscape version via a double click.

However, eclipse does this for a reason- so you don't get confused and bork your files up.

I would think you also could edit these files in a text editor to the side with little loss of efficiency.