I never touched Furmark with a 30 foot pole after I heard its kills HD 4000 series.
You might like the higher number but that doesn't mean it means anything, even proper benchmarking tools hardly reflect gaming performance. If you really want to see how much of an increase you got by adding the extra card then use Crysis' benchmarking tool and then take out a card.
If you really want a nice pretty windows score then you can set your own if you really want, a nice little search of mine found this...http://www.vistax64.com/tutorials/169907-how-hack-your-windows-experience-index-scores.html
Personally I would find that the biggest waste of time but anyway. Now you can set it to what you think it should be...
Hope I helped.