I don't get why they didn't just put the bar say 1cm higher than it had been before... May well have been within the rules to just say they didn't want to do a jump off, but doesn't seem to be in the spirit of things to me.
In some ways it was nice to see them celebrating together as friends, but in another way it just made a bit of a mockery of the whole idea of competing to win if you can just decide not to find out who the winner is and guarantee yourself a gold medal rather than potentially getting the silver.