Bug 9535 - Patron card creator "Remove duplicates" function doesn't work

Bug 9535 - Patron card creator "Remove duplicates" function doesn't work

This bug was due to a difference in field names used in the item data
for items versus patrons. This patch adds a ternary to discern between
the two.

To test:

Before applying patch:

1. Create a batch of patroncards with one duplicate.
2. Run the de-duplication on the batch.
3. Note that all patrons beyond the first in the batch are now
   deleted.

After applying patch:
4. Repeat steps 1-2.
5. Note that only the duplicate patron is removed.

Signed-off-by: Chris Nighswonger <cnighswonger@foundations.edu>
Signed-off-by: Owen Leonard <oleonard@myacpl.org>
Tested successfully with both patron card batches and label batches.

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Add indentation for readability
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>