should 7.1 movie say 7.1 going in and 7.1 going out on receiver?

hi i have a new onkyp rc 460 i have tried the 7.1 set up with the left and right suround backs and set it up on the receiver.. i copied the blu ray movie abraham lincon vampire killier (7.1 sound) to may hare drive and used my wd tv live to play it back,but when i try to hear the sound from the rear back sorrounds they are not discrete they play the same sounds as the left and right surounds..then when i push info on the receiver it says 5.1 dts coming in and 7.1 going out...am i doing something wrong? i thought the movie said it is in 7.1 should it not say 7.1 going in and 7.1 going out? thanks