Or if you want to copy a group of items:
1) click just outside of the group within the screen
2) click again and hold theshift key and left mouse button and drag the mouse across the group
3) a green rectangle should now be around the parimeter of the group, indicating that you have grabbed the group
4) Ctrl-C to copy
5) goto your other screen, and click anywhere in the screen
6) Ctrl-V to paste
7) you will notice that the group (or individual item) will be at the same x,y cordinates from where you copied from.
Have fun.
A more advanced way
1) is to give each item you want to copy from screen to screen a name in the Default/ID window
2) check off the box next to "Multi Screen"
3) click on the "Advanced" tab
4) In the top window of the Advanced tab, you will notice all your screen names under "Multi Screen Button"
5) select which screens you want that item to appear on.
The nice thing about this is if you make a change to the item on one screen, then it is reflected on all the screens the item appears on.