Yes, DMVPN can be used as a backup for MPLS. You can use OSPF as the routing protocol or if your MPLS is using BGP you can redistribute the routes in EIGRP. Following config may help you to redistribute the routing between MPLS and DMVPN
MPLS 2620
router eigrp 1
redistribute bgp 65001 metric 100000 10 255 1 1500 route-map bgp-to-eigrp
passive-interface BRI0/0 network 198.42.128.0 default-metric 1544 20000 255 1 1500 no
auto-summary no eigrp log-neighbor-changes !
router bgp 65001
no synchronization
bgp log-neighbor-changes
router eigrp 1
network 1.7.126.0 0.0.0.255
network 1.7.177.0 0.0.0.255
network 1.7.178.0 0.0.0.255
network 192.191.214.3 0.0.0.0
network 198.42.128.0
distribute-list DEALER-IP-ADDRESS out Tunnel0
distribute-list DEALER-IP-ADDRESS out Tunnel1
distribute-list DEALER-IP-ADDRESS out Tunnel2 distance eigrp 180 175
no auto-summary