I never have, but you'd be able to do it... This is a guess, cos i don't have two users so i can't find out - but if you were in the user profile you wanted to put the songs into, trying going... Macintosh HD > Users > and then selecting which ever user your itunes songs are in... then Music > iTunes and they should be there.
That is, if you can get into the other user folder. *shrugs* Then i'd think you'd just be able to drag drag/duplicate those songs into a folder in the other account.
However, i'm not sure if that'll work, i'm just guessing. Someone might have a better idea.