Controller Based WLANs

Question:  Can you run multiple GRE tunnels between the same two controllers using the same tunnel endpoints?
Environment: This article applies to all the Controllers and OS versions

Yes. However, we would need to configure each GRE tunnel with a different tunnel ID. You can also tunnel multiple VLAN data in a single tunnel.
 
Also, important to note is prior to ArubaOS 6.0 , heartbeats would be sent on every GRE tunnel for a BSSID and/or Wired AP port. This would add a significant load to the STM process if there were many APs on a controller , and many active wired AP ports per AP.

As of ArubaOS 6.0, the heartbeat/keepalive mechanism was modified so only one set of heartbeats/keepalives were sent per AP.