Hello Russell
When you set up multiple next-hops in a Policy-Based Routing (PBR) configuration, the Cisco router will not load balance the traffic among them. Instead, it will use the first valid next-hop in the list and send all the traffic to it.
The router will only move to the next next-hop in the list if the first one becomes unreachable. In other words, it works in a failover manner rather than load balancing.
However, if you want to distribute the traffic across multiple tunnel interfaces, you might want to consider using ECMP routing if your network design and requirements allow it. But this requires that you abandon the use of PBR. More about ECMP can be found at this NetworkLessons note.
I hope this has been helpful!
Laz