how to replace a 2 way double switch ?

i am replacing a 2 way double switch and thought I had noted all wires and terminals from old switch but when connected its not working correctly. there are 2 switches and 2 lights one at bottom of starirs and one at the top / both lights were ok before i tried to repace the top one/ excluding earth wires (3) ist cable yellow red & blue (both red/blue test live ) 2nd cable same colours but none live( could this be a ring loop ? 3rd cable black & red (red tests live) i didnt do the original wiring so am not sure what all the cable are / can any body help