i use 'duplicate task' in the 'more actions' menu very often on the web, but i recently became an ipod app user. The way i duplicate tasks is part of somebody's scheme, i forget which. But it's like:

but thingy.
duplicate.
mark original complete.
edit new one to say "install it"
duplicate
mark original complete.
edit new one to say "doesnt work, return"
duplicate
mark original complete.
edit new one to say "make sure i get my money"
etc

This works very well for me, but i dont see a way to do this in the ipod app, except to edit the task, copy its text, complete it, make new task, paste. And that doesnt get notes or tags.