In the real world, do they ever build only one of anything? Even NASA had an extra Skylab in case the first one didn't make orbit or something.

If there was another DS, what if you could justify capturing it and using it against a bigger threat? The debate over that could tear at the new Republic's fragile seams.

Maybe they changed it since the early days of the ride, but you could see the Death Star blow up on the cockpit monitor that showed Artoo and rebel pilots.

http://www.youtube.com/watch?v=84Vy8DgSXv0

You can see it at 8:02