Betting Advice

A mate of mine has just asked me to work something out for him. He has a nice chunk of cash riding on a football coupon this week and is waiting on 2 results from todays Europa League. How many win doubles would he need to place to cover all possibilities ? I told him there are 9 possible different outcomes over the 2 matches, obviously he already has 1 double in his accumulator so needs to cover the other 8 if this is what he wahts to do , have I worked it out correctly ?
Or is there a better way of covering these ? Or even just let it ride ? Any info or advice appreciated.