Double click on each of the duplicated items in the Song deck. This will open the song card for each item. Look at the Song number on each of these - if they have two different numbers then it means this item is in the database twice as two separate items.
Look on the 'date added' and 'date edited' fields on one of the song card tabs to give you clues as to who and when the duplicate item was created.
If you 'delete' the duplicate song entry, make sure you answer 'no' to the question 'do you want to delete the cart'.
The same cart / 'song' can be in the Autotrack database more than once, as you may wish to put it in more than one category or similar.
Myriad user since 1998, now custodian of dozens of Myriad,Autotrack, Powerlog and Scoop boxes of many different flavours.