...Situations like these, we tend to take it for granted until all hope is lost and we suffered the consequences. That is also why double-checking everything is the key towards preventing mistakes that would be very costly in the long-run.
I have had this situation several times. You simply double automatically and it is very easy to press the wrong button by mistake. And you will find out that your balance is empty only when you cant make another bet. In any case, you do not need to keep large amounts on the balance sheet.