If it only takes a second for the toner to dry, then how would you get a transfer at all?
I really don’t understand how these things happen.
If the documents were printed one right after the other and ejected from the printer one on top of the other into the tray, it could have transferred at that point, but it would have dried very quickly.
Humidity and pressure can also cause transfer. There are a lot of variables/scenarios.
Place a drivers license or an id in a wallet..next to another id..see what happens..the ink is dry. Sometimes there is a transfer to the wallet or a folded paper.