# Find deduplication key and ID in your output data
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You can see the deduplication key and ID in your output data. The deduplication key is identified by `dataset-objectid-attribute-name`. When you use your own custom deduplication key, your output contains something similar to the following:

```
"dataset-objectid-attribute-name": "byo-key",
"byo-key": "UniqueId",
```

When you do not specify a key, you can find the deduplication ID that Ground Truth assigned to your data object as follows. The `$label-attribute-name-object-id` parameter identifies your deduplication ID. 

```
{
    "source-ref":"s3://bucket/prefix/object1", 
    "dataset-objectid-attribute-name":"$label-attribute-name-object-id"
    "label-attribute-name" :0,
    "label-attribute-name-metadata": {...},
    "$label-attribute-name-object-id":"<service-generated-key>"
}
```

For `<service-generated-key>`, if the data object came through an Amazon S3 configuration, Ground Truth adds a unique value used by the service and emits a new field keyed by `$sequencer` which shows the Amazon S3 sequencer used. If object was fed to SNS directly, Ground Truth use the SNS message ID.