wiley bridgeman , 60 , and kwame ajamu , 57 , sentenced for 1975 killing .
key witness , 12-year-old boy , later recanted his testimony last year .
ajamu spent 27 years in prison , bridgeman spent almost 40 behind bars .
third inmate , ricky jackson , received $ 1million in march .
ajamu and bridgeman , who are brothers , received death sentences at age 17 and 20 , respectively .