Duplicate Events - How do I move participants?

So... there was a mistake made where our event staff made two event records for the same event, then made two event forms so they both have participants and I didn't catch it until after the event. Oof. I've talked to her and we're making sure it doesn't happen again AND I need to figure out the best way to fix this. I need to get all of the participants added to the 'real' event record and delete/archive the extra event record


And is manually moving each participant the best way? Or how could I do an import? Or is there another way to do this? 


I'm super underwater right now since I'm covering my rapidly-expanding position AND my open data entry position's work so I'm really hoping there's a faster route than just manually re-entering all of the registrants