I did know about the getting them again, even though you already have them.

I also found a semicheat that if you pause, grab 2-3 kids and put them on that item (must be uncommon or rare to work) the kids will all pick it up.. so there are 2-3 of that item, and you'll get the tech points for them along with the first of the item. Be quick, because pause doesn't pause the item, but the kids so you can grab them faster.

Some of the items, such as rare, I have seen bring in 1k in points for one.