Hi Wibley,
I realise your post is quite old, and maybe Crescendo couldn't do copy/paste in 2011, but now copy/paste can be done at the bar level, which means you can copy whole bars (including their notes), but not individual notes. To copy a bar, first select it by clicking within its staff. You should see it change color. You can select more than one by holding down the shift key as you click. Cut or copy with Ctrl+X or Ctrl-C, then select a different bar to paste into. Pasting will replace the contents of the selected bar, so if you don't want to erase anything make sure you paste into an empty bar (use Insert Bar or the bar line tool to make an empty bar).
Alex