In campaign mode I hurriedly clicked on Revive party, accidently double clicking it and was charged per click... would be curious to see just how many clicks you could get in and if you would indeed be charged for each one but I don't want to waste the gold!
My mouse is broken and tends to double click, so I have experienced this bug rather a lot. Not normally a problem, but has made doing difficult quests very expensive.
In your specific case. Why don't you download software allowing you to reconfigure mouse-buttons? You could bind a mouse-button you don't use, to mouse1. Interesting bug though. A shame it doesnt work on "take all"
I wonder what would have happened if you reloaded the game. It might have only charged you gold once, since this is a client-side thing. It would be a bug if the server accepted the second charge.
I'll check it next time I try a quest or find another excuse to kill off all my guys, and let you know.