in this guide i will explain to you the following :
What is DMVPN with Dual Hubs?
Lab 1 DMVPN Dual Hub in Single DMVPN network
Lab 2 DMVPN Dual Hub in Dual DMVPN network
kindly read the following articles i wrote about DMVPN for CCIEv5 R&S before reading this one .
CCIEv5 DMVPN Labs Workbook
CCIEv5 DMVPN Quick Guide
Yasser Ramzy Auda