I have no idea who took the coins. Probably never will. And I don’t know what kinda person they are. Like, if they were honest, they would’ve seen it, realized it was probably a mistake, maybe taken the forked coins, hit me up, and asked for a reward or something. That would’ve been fair. A selfish person would’ve just grabbed it and been like, “Wow, free money, lucky me!” But a shady person—the criminal type? They look for stuff like this. Waiting for someone to slip up so they can pounce.
It's the old saying: "opportunity makes the thief". In this case, it looks like whoever took it regretted it, and returned it only for a second person to take it. It would have been much better to ask for a new address to send it to. Those are rookie mistakes, just like you made a rookie mistake by showing the key.