It is possible to use the same license key for a second node activation?
To set up the cluster nodes you should have the license with 2 activations.
Another way is to purchase 2 licenses:
- in this case, the first license will be the main one with most of the pages and the second one will be used as a backup for the second cluster node.
Full scenario for clusters described here: Working with Clusters
Please note that there are hardware requirements for the Failover clusters: