This is what I call a classic "I Never" moment. You know, "I never imagined someone would put me in a situation like this..." Unfortunately, it happens among friends more often then we would like and it's usually due to someone having poor judgment when it comes to friendship and boundaries. These two friends definitely crossed a boundary and acted, in my opinion, disrespectful towards you and the rest of the people there. You did the right thing in standing up for yourself and others there, as this kind of thing could have happened again if it went unchecked.
My mind is racing as the "jerk side of me" thinks of all kinds of ways you could have handled this situation.
You could have gone on the offensive, "what the hell did you guys order..."
You could have been passive aggressive, "hey guys, somethings wrong with our bill the silly waiter mistakenly put some really expensive wine on our tab, I'll have him take it off..."
You could have played dumb, "Did you guys order some wine??? Goodness gracious, look at the bill, let me get the waiter to split that for you two..."
You could have broke crazy, (smashes empty wine bottle on table and holds up jagged edge as a weapon) "you too selfish drunks will be paying for your own habit right, cause I ain't afraid to cut ya..."
Don't be surprised if you lose some friends over something silly like this. If it does turn into a big deal just stand your ground with simple reasoning, "I would never expect someone else to pay for something like that if I did it. I don't want to impose on those around me and appreciate it if I'm extended the same respect."