Playlists in iTunes?

[Feek]

I've been paying attention to last.fm and grabbing some of the stuff that it thinks I'll like such as 3 Doors Down, The White Stripes and Kasabian to name but a few.

I sync my iPod using a main playlist, that is that I have all tunes ticked in the main 'music' playlist but have a sub list 'Feek's iPod Touch' which I've added all the music I want synced to. I don't sync the main music list but I do this secondary one.

So I've added the new music I got to the Feek's playlist, it all syncs. Great.

If I were to make another list called 'new stuff' and add the new tunes to it and tell iTunes to sync that playlist to my pod, will it dump two copies of all the songs to it, or is it all intelligent enough to realise that it's the same music and only put a single copy out but flag it for multiple playlists?