simplified duplicate checking
simplified duplicate checking


Former-commit-id: dd2e0d5653be1f0e69ff66d0dfd57cd3e7cc33c2 [formerly dd2e0d5653be1f0e69ff66d0dfd57cd3e7cc33c2 [formerly 3ce8bbeae286c6959e16de4fe063c6c0cba2806f]]
Former-commit-id: 7a9ebe0866da12b2e67a9350c513369f17acc8e4
Former-commit-id: fd3eadd62ec7082472c239540c2214be6cbe3797
gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine,gem/oq-engine