The error is typically seen when SDM version 2.3.1 is used and the user tries to add more tunnels with the existing ones.
In order to resolve this issue ,download and upgrade to Cisco SDM version 2.3.2.
For more information on how to configure the DMVPN tunnel, refer to Dynamic Multipoint IPsec VPNs (Using Multipoint GRE/NHRP to Scale IPsec VPNs).
Refer to the Prerequisites section of Dynamic Multipoint VPN (DMVPN) for more information on the minimum requirements you need in order to set up the tunnel.
For more information, refer to the DMVPN Hub Wizard section of the SDM 2.5 User Guide.