Haha I had a similar thing. This dude said he would come pickup stuff tomorrow. Well someone came that same night to get it and the next day it was gone. Dude was pissy and probably cried.
IMO You had a deal with guy #1, IF he said "I will take It" and "I will be there tomorrow with cash to pick it up"
If you agreed to that and then sold it to guy # 2 because he came to pick it up earlier, then IMO you broke your agreement and if you did that to me I would be pissy too