Hi Val,
I'm not sure what Allen means by not liking the way it is now, because duplicating lines still isn't working at all...nothing happens in any way when you choose that icon.  As far as how it should work, it makes more sense to me that it should duplicate immediately after the line you're on, but it really doesn't make that much of a difference.  Usually you are duplicating a line while entering the PO so you are already at the end of the lines (since you haven't entered any lines after that one yet).  I hope that makes sense.