Hello Marlon
Welcome to NetworkLessons! Great to have you with us, we hope you find the lessons and the forum useful to you.
There are many DMVPN lessons found on the site, the first of which is the following Introduction to DMVPN lesson:
You can start there and look through all the lessons. Now there is no lesson that addresses redundancy at the spoke using multiple ISPs. If you think that this would be a good lesson for Rene to create in the future, please feel free to let us know here on the Member Ideas page:
You may find that others have made similar suggestions, and you can add your voice to theirs.
In the meantime I can share with you that the use of redundancy at the spoke using multiple ISPs has become common practice, where one ISP is used as the primarily connection, and the other acts as a backup. One way to do this is to use VRF-Lite to segregate the routing table when a spoke has dual ISPs. With VRF-Lite, multiple VPN routing instances can be supported on the DMVPN spoke. An example of how to configure this can be found in the following Cisco documentation:
I hope this has been helpful!
Laz