Error when editng the"Sound" Item Type

I am attempting to add new elements to the "Sound" Item Type, but receive the following error:

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Element #4: Name: 'Composer' already exists for element set #3

Element #5: Name: 'Librettist' already exists for element set #3

Element #6: Name: 'Conductor' already exists for element set #3
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Previously, I created Items containing the following input:

Creator:
Composer: Giuseppe Verdi
Librettist: Joseph Méry
Librettist: Camille du Locle

Contributor:
Conductor: Carlo Maria Giulini

Could this be the cause of the problem?

Thanks!

I figured it out; I did not realize that if you add a new element in any of the Item Types, then it will be available for all of the Item Types. I failed to connect that these are all managed via a Mysql database. Resolving.