if you plan on doing it without BGP you would need to do something like this.
Tag-Based IPsec VPN Failover - Cisco Meraki Documentation
When you configure two static tunnels towards the same network segment the traffic will flow across both tunnels at random i think.
A better solution would be to do site to site with BGP peering. It's available from MX19.1 and up, so quite fresh. But it could be worth looking into.
MLL