I unfortunately don't have a good set of Before/After save files, but here's the description anyways.
I had a red toolbox I used specifically for deliver-to-NPC quest items. I went out and delivered all 5x items and was able to return to a gig kiosk for the full payouts... but now that I look in my toolbox I still have 3x of the items.
Not gonna lie, a free purple jumpsuit was a nice surprise, but it very much seems like this is not the intended game mechanics for item delivery quests.