Bought used (auction) PC on Mercari seller proceeds to list the same PC on Yahoo furima (auction)

A couple of days ago I entered an auction for a used PC on Mercari. I ended up getting lucky and won the auction for a decent amount under market price. (about 2 man cheaper than the next cheapest option)

I exchange formalities with the seller after paying and they tell me to wait until they ship the item. The seller listed time to ship as 4-7 days after purchase. I think, no big deal, as long as it eventually arrives. The seller has a 4 and a half star rating, surely they are an honorable gent.

About 4 days after paying the final auction price the exact same photos and description appears on an auction post on Yahoo furima. Coincidentally the auction ends the same day of the original seller's shipment deadline. The yahoo furima account has no ratings except for 1 bad. Looks like they are planning to cancel my shipment if they get a better deal on the other site.

I still really want the PC but not a huge deal if it doesn't pan out. Should I just hope that nobody beats my auction price on Yahoo furima?

I looked up the rules on Yahoo Furima and it's against the rules to put up the same product on more than one site; it's okay to do on the mercari side of things though. I know it sounds petty, but maybe I can report it and get it taken down? I'd call them out on it but I doubt they'd care.

by Equivalent-Movie7811