How do you stop names from doubling - Views
If I had to guess, I'd say your "Look up Leaders" functionality is built with Views in Drupal or Backdrop, and it shows up double because there are two different "Other" phone numbers for these contacts. It's treating them as two different entries.

If that is the case and if it's possible to remove or relabel the second phone number location type in the contact records (ie. not have two "Other" phone numbers -- although you could have multiple phone numbers if they have different location types) I think it would solve the issue.

EDIT Upon closer inspection, the second "Other" number appears to duplicate the "Mobile" number. In the contact record, try deleting the duplicate number with the "Other" location type.