How to apply "Remove Duplicates" on each attribute of an example set?

Hello everyone,

I'm a total beginner with Rapid Miner, and I apologize if my question is an obvious one or if it has been posted under another title. I work in Humanities, so I'm usually not very familiar with computing. However, Rapid Miner has given me amazing results so far, and I'd like to dig further.

I have a dateset of songs in which, for each Title, I have all the Artists involved in an column, all the Songwriters in a second column, and all the Producers in a third. I have been able to split these columns in order to have only a single name per box (Artist_1, Artist_2, Songwriter_1,...). The issue I have is that, for each song, an artist can also be the songwriter and/or the producer. I would like to get the name of each person involved only once.

As I have 60.000 songs, I first thought to do a Loop to automatically select one song after the other and apply "Remove Duplicates" for each of them. I would have expected a collection of individual sets, i.e. each song with only each name once. But I can't figure out how to automatically select only one song after another... 

I hope my description is clear enough.

Thank you for your help :-)