Bug 18482 False duplicates detected on adding a batch from a stage file

Bug 18482 False duplicates detected on adding a batch from a stage file

When adding a batch from a stage file with defaut matching on
title/author, if a duplicate is detected, all following records
treated in the batch are discarded from import even if they are not duplicates

Signed-off-by: Alex Buckley <alexbuckley@catalyst.net.nz>
Signed-off-by: Jonathan Druart <jonathan.druart@bugs.koha-community.org>
Signed-off-by: Kyle M Hall <kyle@bywatersolutions.com>