Why two IPsec tunnels from two physical interfaces on one router to one physical interface of remote host won’t work? One of the tunnel is disabled (red in winbox). In this configuration this should work like load balancing (two routes to the same network with the same metric). This is only part of configuration file.
ip address add address=1.0.0.2/30 broadcast=1.0.0.3 disabled=no interface=public network=1.0.0.0
ip address add address=3.0.0.2/30 broadcast=3.0.0.3 disabled=no interface=public network=3.0.0.0
ip address add address=172.22.1.1/24 broadcast=172.22.1.255 disabled=no interface=inside network=172.22.1.0
ip route add disabled=no distance=1 dst-address=0.0.0.0/0 gateway=1.0.0.1 scope=30 target-scope=10
ip route add disabled=no distance=1 dst-address=0.0.0.0/0 gateway=3.0.0.1 scope=30 target-scope=10
ip ipsec policy add src-address=172.22.2.0/24 dst-address=172.22.1.0/24 action=encrypt tunnel=yes sa-src=1.0.0.2 sa-dst=2.0.0.2
ip ipsec policy add src-address=172.22.2.0/24 dst-address=172.22.1.0/24 action=encrypt tunnel=yes sa-src=3.0.0.2 sa-dst=4.0.0.2
Where 2.0.0.2 and 4.0.0.2 are interfaces of Ipsec tunnel on other end.