@VintageVulpix asks
I meant to trade my duplicate but accidentally handed over the nicer copy. Can I ask to swap them?
Jeff answers
I'd contact the other person promptly and explain exactly what happened. Ask rather than assume they're obligated to change a completed trade. This is why I separate available copies before an event. If they agree, confirm which cards are being exchanged back so the correction stays clear.
— Jeff, infinitepulls.com