I'm not sure about this one
Nothing could ever beat the original, Meat belting it out with the orchestra, and I don't think that anyone could recreate the feeling he does when he sings it. However, I have a live version of FCOL ( nice one Ewan
) and there's a tiny bit of harmony on the line For Crying Out Loud, and it's only on that line, and it's really effective! But it is just one line and I don't know that it would have quite the same effect if the whole song was harmonised as a duet
Lucy