The check is made locally by the tasks inbuilt script, so the task will be received by all machines but the first local check will be 'do I already have that product ?'
If the response is yes, then the task just ends at that point for that machine.
We don't assume that because the DB says it's installed/not installed the same is true locally.
After all it could have been installed/uninstalled locally and independently of ePO inbetween.
Excellent. Thanks for the most informative answer