Change to double crankset, change shift levers too?
Hi, I'm almost a newbie here but please bear with me because I need some help. I have a bike with Shimano 105 crankset, 105 shift lever, and Flightdeck computer. I switched to a double crankset (dealer offered me that option to make more of a racer). Now when I shift the double, the computer does not register the downshift unless I shift twice! The dealer says this is because the 105 shift lever is a triple still and I would need the double to make it work without the glitch. I researched a little on the internet and could not find different double versus triple versions of the shift levers. So could he be mistaken? If so, how does one go about setting the shifter to double? Thanks, maybe should have let well enough alone.