Even if you have 'Let It Come Down', its worth getting both singles for the extra tracks. CD1 contains a blistering version of 'On Fire' taken from the Evening Session last year, and the first recorded material from the 'new' Spiritualized. "Amazing Grace" (Peace On Earth) is a wonderfully deconstructed version of the classic song, which sounds just like the headfucking jazz-noise outbursts that the band play live.
CD2 contains another Evening Session track, a completely different version of 'Do It All Over Again' in which the pace is slowed down considerably and Pierce sounds wrecked, which then leads into a excellent version of 'Come Together'. Plus you get an instrumental version of 'Out Of Sight''s B-side, 'Going Down Slow', and the video to the single, which, if you haven't seen, you really should.
So get them.