I've had to rebuild a workflow in 2010 because I need it to be kicked-off from another workflow. I learned here before that to get a workflow to NOT keep re-sending a task if the list is modified, put a flag on the WF and have it change to true or false then the statement won't be true anymore to re-send the task each time the workflow is modified. For some reason this isn't working in 2010. The flag does change to "YES" for me, but that's not preventing the task from being re-sent. Any ideas?
Instead of using Update item, use Set field in Current Item. In my experiences, the action "Update item" will trigger, which is essentially starting another workflow. This ghost resending of tasks may be the other workflow coming up behind you and finishing out its actions.