DMVPN redundancy options
DMVPN delivers a hub and spoke topology. This introduces a single point of failure at the hub. Redundancy can be implemented with the use of a second hub. There are two ways to introduce such redundancy:
If you choose to, you can have DMVPN with more than two hubs but this should be done with the appropriate considerations.
Links
https://networklessons.com/cisco/ccie-enterprise-infrastructure/dmvpn-dual-hub-single-cloud
https://networklessons.com/cisco/ccie-enterprise-infrastructure/dmvpn-dual-hub-dual-cloud