Currently Being ModeratedDec 1, 2012 2:25 AM (in response to John Lockwood)
Thanks John - what I think has happened is that the 'extra' songs are ones that he bought a few years ago when he was using my Apple ID; now he's old enough to have his own! So that explains it - I assume this is a feature of iTunes 11, to show these 'cloud' songs.
I also noticed that one of the albums I had bought from iTunes, that has always been in my Library, is showing twice in iTunes 11 - the original in the Library and a duplicate in the Cloud - I say 'duplicate', but the track lengths are different by a few seconds.
I think this means that iTunes has recognised that I have bought and downloaded the album, but the current version they have in Store is slightly different to the version I already bought.