1) Thats where fraud protections comes to work for you
if you have it, if you contact your bank and point it out. Depending on your bank/CC they will revert and deny the 2nd charg and revert the fund's to your acc instently for most banks, now CC like chase/captialone have a free feacher where they auto decline the 2nd charge till you respont to the txt/automated phone call thats free.
2nd) Any thing bough online via with dc/cc/ba, it is a must to have the extra protection or you can be waiting 6 mth's for your funds to come back to your acc.. Trust me I learned the hard way with M$ charging me 4 times for 1 item which contently almost put me on the street's living after it wiped out my whole bank account.