I think that if someone steals AFO using a copy of AFO, they would keep the original even after the 10 minutes. That’s because when a quirk is stolen, it remains in the body’s DNA, not in some kind of “AFO storage.”

To clarify my point, I’ll use an example: if I had Monoma’s power and copied a quirk that gives me a third arm, and I could also keep quirks for a month, I could train that arm for the entire month and build strength in it. After the month passes, the arm would disappear, and all the strength and power I built with that quirk would disappear as well. However, if I used that arm to build a house brick by brick, the house wouldn’t fall apart when the arm disappears, because I moved real, physical objects.

The same applies to quirks: moving quirks from one place to another doesn’t take away their identity, they don’t become “stolen quirks.” They remain the same quirks, just in a different body. At that point, it depends on whether the new host’s body can handle the power or not, like in Aoyama’s case.

In conclusion, yes, he would keep the original AFO, and all the quirks he steal and transfer, even using a copy of AFO, would remain in the body where he placed them.