this happened with a sale i was doing the other day. Had a couple offer 830k ... which the owner accepted on a saturday morning. Someone came in on saturday afternoon and offered 835k. So we basically told both parties someone else was interested and whoever could exchange first at 835k would get it.
How did the owner accept? Guessing just a verbal confirmation?
Goes to show peoples word doesnt mean anything until they sign.. bit rude I think..