fix issue where matching results blanked out repeated answers

fixes CNVS-10613

test plan:
 - create a quiz with a matching question
 - have one answer on the right side be a duplicate
 - take the quiz and answer correctly
 - when viewing the results the answers should all show up correctly
 - try this same with multiple duplicates
 - do general regression testing around matching questions

Change-Id: I711c9df59c17f99e2d4ddb25b79b9e9679e1be8c
Reviewed-on: https://gerrit.instructure.com/33467
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Josh Simpson <jsimpson@instructure.com>
QA-Review: Caleb Guanzon <cguanzon@instructure.com>
Product-Review: Derek DeVries <ddevries@instructure.com>