In 7-mode there were two keys required, and in ONTAP9 there is only one. The one key activates both features.
From the Data Protection and Disaster Recovery Guide:
"A SnapLock license entitles you to use both SnapLock Compliance mode and SnapLock Enterprise mode. SnapLock licenses are issued on a per-node basis. You must install a license for each node that hosts a SnapLock aggregate."
The extra key is still useful if you were to build a 7mode simulator on 8.2.x using that serial number.
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