There are several reasons to have double triggers on a DR.... One is, some folks like to carry two different styles of bullets in each bbl., like a solid in one bbl., and a soft point in the other... Or maybe two different bullets weights?
But, the best reason of all is, doubles are really two guns in one, that are side by side. If one side fails the other side still works perfectly....that is "if" the gun has double triggers! It's all about reliability...
As for two trigger pull weights, i'll bet that you will have two different pull weights with a single trigger too... That happens mostly because of sear enguagement, and a double has two sears no matter how many triggers it has.
Another thing, if you have double triggers on one gun, wouldn't you want double triggers on the second one too? Why give yourself yet "another" thing to think about when your in a hunting situation?
Make mine, double triggers please...
DM