Somethin' funny goin' on fer sure there. Well, Hex Tronic makes stuff for HK, so both of your boards came from their manufacturer, Hex Tronic. Maybe not by the same retailer but from the same supplier of FCs. If I were you I'd try and find out what kind of baro that is on the bottom board before you actually try to fly with it. Also in your Arduino config.h sketch you will need to uncomment the correct statement in the "boards and sensor definitions" section of the sketch. To do that correctly you will need to find out what version you should uncomment from the seller. For the one in the top picture it will be //#define FFIMUv2 // second version of 9DOF+baro board from Jussi, with HMC5883 <- confirmed by Alex
Since the bottom board doesn't have the same baro, it most likely can't use that version. From what I see, there are 9 different versions of those Mega boards. Maybe yours is the one with no baro at all. Does the device in the baro position have a little hole or holes in it? If not than it is the non baro version //#define FREEIMUv035 // FreeIMU v0.3.5 no baro. That is stuff you will need to know to get the board flying.
Also, I would say that SA.com sent you what you bought. HK didn't. They sold you something else than what they have advertised on their own site. Did both boards come with an MTK GPS? Because that is what they say they are selling.