1.   He let himself in with a duplicate key.

2.   I had a duplicate key made.

3.   The front desk apologises for the inconvenience and they accompany him back to his room with a duplicate key.

4.   The escapees had a duplicate key, and were gone for nearly two hours before the alarm was raised.

5.   The escapers had a duplicate key, and were gone for nearly two hours before the alarm was raised.

6.   The guerrillas surprised their guards at the Madras Central Prison after opening their cells with duplicate keys Monday night.

7.   Using a duplicate key, U.S. and German authorities entered his room and found him inside.

8.   Police said the thieves used duplicate keys to get in to the Cypriot embassy, stealing several hundred francs.