If there is a lack of data scrubbing prior to getting the list of new people to insert into holo, many duplicates end up existing. The current behavior of holo is to not insert any of the set of people if there exists duplicates, which could be a lot of additional time-consuming work if 20 people are being added and one duplicate ruins the set.
If a duplicate is present, it should be ignored while the others are correctly inserted, and the duplicates should be printed out (and preferably logged #12)
savoy referenced this ticket in commit e04c987.