Categories field that allows duplicate values I have a categories field where I would like to be able to include the same category more than once. Any suggestions on how to do this?
I'd probably go with a Matrix field, with one block type containing the Categories field. This would also allow you to include other fields for some extra meta data to distinguish one category assignment from another, otherwise identical one.

To use your playlist example, the Matrix blocks would let you set the order of the tracks as well.