Duplicating Prims

Is it possible to duplicate your prim without it jumping to another spot.
It's a pain to try to re-align them or enter the number in when I just wanted the shape to be straight up or straight down from the original.
And why do some of the prims I duplicate not have duplicate permissions themselves?

I take it from the "jumping around" statement that you're using ctrl-d to duplicate. That method always gives you a .05M offset on X and Y, which can be kind of annoying, as you say. Try this instead. Select the prim(s) you want to duplicate, hold down shift, and then drag any of the 3 manipulator handles (directional arrows). You'll move the object in the direction of the arrow and in its place you'll leave behind an exact copy. If you want the original to go back to where it was afterwards, just press ctrl-z to undo the movement.

Another way to do it if you want the copies to stack perfectly is to turn on "copy selection" and "center copy" on the build tool. First, select the object you want to copy, then select the build tool, turn on those two options, and then click with the magic wand thingie on any surface of the orginal. A new copy will appear, centered on whatever surface you clicked on. If you want the new one to be on top, simply click on the top of the old one.

Thanks, that's very helpful!